docs: adds claude.md files

[lucasloisp]

Summary

Adds CLAUDE.md files to give AI assistants (Claude Code and similar) structured context about the repo.

• CLAUDE.md (root) — repo map, commit conventions, release process, and a pointer to SDK/CLAUDE.md
• SDK/CLAUDE.md — SDK-specific guide covering package structure, the interface/implementation architecture pattern, DI wiring, code formatting command, XML doc requirements, and pointers to existing docs for versioning, native plugins, and DI details
• SampleApp/CLAUDE.md — one-liner describing what the sample app is
• docs/dependency-injection.md — new doc covering constructor injection, wiring in PrivyImpl, and null-checking patterns

Kept intentionally lean: conventions enforced by the linter/editorconfig are not duplicated here, and sections that would restate existing docs/ content link out instead.

Testing

Reviewed content against agent_docs/pr_review_rules.md, docs/releasing.md, docs/native-code.md, and the existing SDK source to verify accuracy. Ran a Codex adversarial review — no findings.

Public package change?

• Update the CHANGELOG.md file.

[lucasloisp]

• docs: adds claude.md files #36 👈 (View in Graphite)
• main

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