Add AI agent friendly GitHub configuration

[klboke]

Summary

• Add Copilot repository instructions plus path-specific instructions for server, protocol compatibility, frontend, and docs work.
• Add custom agents for protocol review, test writing, docs sync, and security review.
• Add an agent-ready issue template, a reusable compatibility-risk prompt, and CodeQL scanning.

Repository settings updated outside this PR

• Enabled Copilot review-on-push ruleset earlier.
• Enabled auto-merge.
• Enabled delete branch on merge.
• Enabled Dependabot security updates.
• Added the agent-ready label.

Verification

• YAML parse for issue template and CodeQL workflow
• Front matter parse for agents, instructions, and prompt files
• git diff --check
• JAVA_HOME=/opt/homebrew/Cellar/openjdk@25/25.0.3/libexec/openjdk.jdk/Contents/Home mvn -pl server -am -DskipTests compile

[Copilot]

Pull request overview

This PR adds AI-agent and automation tooling to the .github directory of kkRepo (a Nexus-compatible self-hosted artifact repository). It introduces repository-wide Copilot instructions, path-scoped instruction files, several custom agents, an agent-oriented issue template, a reusable compatibility-risk prompt, and a CodeQL scanning workflow. The content faithfully mirrors the engineering rules, module responsibilities, and build/test conventions already documented in AGENTS.md, and the action versions/Java baseline are consistent with the existing ci.yml.

Changes:

• Add Copilot instructions (copilot-instructions.md) plus applyTo-scoped instruction files for Java server, protocol compatibility, frontend, and docs.
• Add four custom agents (protocol-compat reviewer, test-writer, docs-syncer, security-reviewer), an agent-task issue template, and a compatibility-risk triage prompt.
• Add a CodeQL workflow analyzing Java with security-extended/security-and-quality queries.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/workflows/codeql.yml	New CodeQL Java analysis on PR/push/schedule; versions match existing ci.yml.
.github/prompts/compat-risk-triage.prompt.md	Reusable prompt; front matter uses unrecognized agent: key instead of mode:.
.github/ISSUE_TEMPLATE/agent_task.yml	Scoped issue form for agent tasks with agent-ready label and validation command.
.github/instructions/protocol-compat.instructions.md	Protocol-compatibility guidance scoped to protocol/compat-test/server services & controllers.
.github/instructions/java-server.instructions.md	Java server guidance scoped to backend modules; aligns with Java 25 + -am build rules.
.github/instructions/frontend.instructions.md	Admin/browse UI guidance favoring operational, information-dense layouts.
.github/instructions/docs.instructions.md	Docs guidance keeping docs/en/docs/zh aligned and claims tied to behavior.
.github/copilot-instructions.md	Repo-wide Copilot rules covering modules, distributed state, build/test, compatibility.
.github/agents/test-writer.md	Custom agent for adding focused tests.
.github/agents/security-reviewer.md	Custom agent for security-sensitive review.
.github/agents/protocol-compat-reviewer.md	Custom agent for Nexus/protocol compatibility review.
.github/agents/docs-syncer.md	Custom agent for keeping bilingual docs aligned.

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