docs: harmonize issue templates, contributing guide, readme, etc.

.github/CODEOWNERS

@@ -0,0 +1,6 @@
+# Default owners for everything
+* @toon-format/java-maintainers
+
+# Project governance and documentation
+CODE_OF_CONDUCT.md @johannschopplich
+CONTRIBUTING.md @felipestanzani

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,67 @@
+name: Bug Report
+description: Report a bug or unexpected behavior
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to report a bug!
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: A clear description of what the bug is
+      placeholder: When I try to encode..., I expect..., but instead...
+    validations:
+      required: true
+
+  - type: textarea
+    id: reproduction
+    attributes:
+      label: Reproduction Steps
+      description: Steps to reproduce the behavior
+      placeholder: |
+        1. Create a Toon instance
+        2. Call encode() with...
+        3. See error...
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected Behavior
+      description: What you expected to happen
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual Behavior
+      description: What actually happened (including error messages and stack traces)
+    validations:
+      required: true
+
+  - type: textarea
+    id: environment
+    attributes:
+      label: Environment
+      description: |
+        Please provide:
+        - Java version
+        - JToon version (from build.gradle or pom.xml)
+        - Operating system
+      placeholder: |
+        - Java 21.0.1
+        - JToon 0.1.2
+        - macOS 15.0
+    validations:
+      required: true
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Any other context about the problem (optional)

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,48 @@
+name: Feature Request
+description: Suggest a new feature or enhancement
+labels: ["enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for suggesting a feature!
+
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem Statement
+      description: What problem does this feature solve?
+      placeholder: As a user, I want to... because...
+    validations:
+      required: true
+
+  - type: textarea
+    id: solution
+    attributes:
+      label: Proposed Solution
+      description: How would you like this to work?
+      placeholder: |
+        Add a new method/function that...
+    validations:
+      required: true
+
+  - type: textarea
+    id: alternatives
+    attributes:
+      label: Alternatives Considered
+      description: What alternative solutions have you considered?
+
+  - type: textarea
+    id: spec
+    attributes:
+      label: SPEC Compliance
+      description: |
+        Does this relate to the TOON specification?
+        If yes, please reference the relevant section.
+      placeholder: This relates to SPEC.md section...
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Any other context, mockups, or examples

.github/ISSUE_TEMPLATE/spec_compliance.yml

@@ -0,0 +1,65 @@
+name: SPEC Compliance Issue
+description: Report a deviation from the TOON specification
+labels: ["spec-compliance"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Report an issue where JToon doesn't comply with the official TOON spec.
+
+  - type: input
+    id: spec-version
+    attributes:
+      label: SPEC Version
+      description: Which version of the TOON spec does this relate to?
+      placeholder: v1.3
+    validations:
+      required: true
+
+  - type: input
+    id: spec-section
+    attributes:
+      label: SPEC Section
+      description: Which section of SPEC.md is affected?
+      placeholder: "Section 2.3: Array Notation"
+    validations:
+      required: true
+
+  - type: textarea
+    id: spec-requirement
+    attributes:
+      label: SPEC Requirement
+      description: What does the spec require?
+      placeholder: According to SPEC.md, the encoder should...
+    validations:
+      required: true
+
+  - type: textarea
+    id: current-behavior
+    attributes:
+      label: Current Behavior
+      description: What does JToon currently do?
+      placeholder: Currently, JToon...
+    validations:
+      required: true
+
+  - type: textarea
+    id: test-case
+    attributes:
+      label: Test Case
+      description: Provide a test case that demonstrates the issue
+      placeholder: |
+        ```java
+        import com.felipestanzani.toon.Toon;
+        String result = Toon.encode(...);
+        // Expected: ...
+        // Actual: ...
+        ```
+    validations:
+      required: true
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Any other relevant information

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,121 @@
+## Description
+
+<!-- Provide a clear and concise description of your changes -->
+
+## Type of Change
+
+<!-- Mark the relevant option with an [x] -->
+
+- [ ] Bug fix (non-breaking change that fixes an issue)
+- [ ] New feature (non-breaking change that adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Documentation update
+- [ ] Refactoring (no functional changes)
+- [ ] Performance improvement
+- [ ] Test coverage improvement
+
+## Related Issues
+
+<!-- Link any related issues using #issue_number -->
+
+Closes #
+
+## Changes Made
+
+<!-- List the main changes in this PR -->
+
+-
+-
+-
+
+## SPEC Compliance
+
+<!-- If this PR relates to the TOON spec, indicate which sections are affected -->
+
+- [ ] This PR implements/fixes spec compliance
+- [ ] Spec section(s) affected:
+- [ ] Spec version:
+
+## Testing
+
+<!-- Describe the tests you added or ran -->
+
+- [ ] All existing tests pass
+- [ ] Added new tests for changes
+- [ ] Tested on Java 17
+- [ ] Tested on Java 21
+
+### Test Output
+
+```bash
+# Paste test output here
+```
+
+## Code Quality
+
+<!-- Confirm code quality checks -->
+
+- [ ] Ran `./gradlew test` - all tests pass
+- [ ] Ran `./gradlew jacocoTestCoverageVerification` - coverage meets 85% threshold
+- [ ] Added JavaDoc comments for public APIs
+- [ ] Code follows Java conventions
+
+## Checklist
+
+<!-- Mark completed items with an [x] -->
+
+- [ ] My code follows the project's coding standards
+- [ ] I have added JavaDoc comments to new public APIs
+- [ ] I have added JUnit tests that prove my fix/feature works
+- [ ] New and existing tests pass locally
+- [ ] I have updated documentation (README.md if needed)
+- [ ] My changes do not introduce new dependencies (or are justified)
+- [ ] I have maintained Java 17+ compatibility
+- [ ] I have reviewed the [TOON specification](https://github.com/toon-format/spec) for relevant sections
+
+## Performance Impact
+
+<!-- If applicable, describe any performance implications -->
+
+- [ ] No performance impact
+- [ ] Performance improvement (describe below)
+- [ ] Potential performance regression (describe and justify below)
+
+<!-- Details: -->
+
+## Breaking Changes
+
+<!-- If this is a breaking change, describe the migration path for users -->
+
+- [ ] No breaking changes
+- [ ] Breaking changes (describe migration path below)
+
+<!-- Migration path: -->
+
+## Screenshots / Examples
+
+<!-- If applicable, add screenshots or example output -->
+
+```java
+// Example usage
+```
+
+Output:
+```
+# Example output
+```
+
+## Additional Context
+
+<!-- Add any other context about the PR here (optional) -->
+
+## Checklist for Reviewers
+
+<!-- For maintainers reviewing this PR -->
+
+- [ ] Code changes are clear and well-documented
+- [ ] Tests adequately cover the changes
+- [ ] Documentation is updated
+- [ ] No security concerns
+- [ ] Follows TOON specification
+- [ ] Backward compatible (or breaking changes are justified and documented)

CODE_OF_CONDUCT.md

@@ -82,4 +82,4 @@ This Code of Conduct is adapted from the Contributor Covenant, version 3.0, perm
 
 Contributor Covenant is stewarded by the Organization for Ethical Source and licensed under CC BY-SA 4.0. To view a copy of this license, visit [https://creativecommons.org/licenses/by-sa/4.0/](https://creativecommons.org/licenses/by-sa/4.0/)
 
-For answers to common questions about Contributor Covenant, see the FAQ at [https://www.contributor-covenant.org/faq](https://www.contributor-covenant.org/faq). Translations are provided at [https://www.contributor-covenant.org/translations](https://www.contributor-covenant.org/translations). Additional enforcement and community guideline resources can be found at [https://www.contributor-covenant.org/resources](https://www.contributor-covenant.org/resources). The enforcement ladder was inspired by the work of [Mozilla’s code of conduct team](https://github.com/mozilla/inclusion).
+For answers to common questions about Contributor Covenant, see the FAQ at [https://www.contributor-covenant.org/faq](https://www.contributor-covenant.org/faq). Translations are provided at [https://www.contributor-covenant.org/translations](https://www.contributor-covenant.org/translations). Additional enforcement and community guideline resources can be found at [https://www.contributor-covenant.org/resources](https://www.contributor-covenant.org/resources). The enforcement ladder was inspired by the work of [Mozilla’s code of conduct team](https://github.com/mozilla/inclusion).