docs: Add agent rules for API, options, and PR workflows

[adinauer]

📜 Description

Add new cursor rules to guide AI coding agents when working on specific areas of the SDK:

• api.mdc — Public API surface, binary compatibility, key classes to modify when adding new API
• options.mdc — Adding/modifying SDK options across all configuration layers (SentryOptions, ExternalOptions, ManifestMetadataReader, Spring Boot)
• pr.mdc — PR creation workflow, stacked PRs, stack comments, merging and syncing stacks

Updates overview_dev.mdc to reference the new rules with context clues for when to fetch them.

💡 Motivation and Context

These rules capture institutional knowledge that agents need when working on common SDK tasks. Without them, agents miss steps (e.g. forgetting to update ExternalOptions when adding a new option) or don't follow established patterns (e.g. stacked PR naming conventions).

💚 How did you test it?

Reviewed the generated rule files for accuracy against the existing codebase patterns. The rules are documentation only — no runtime behavior changes.

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

Add more domain-specific rules as patterns are identified (e.g. scopes, offline/caching, metrics).

#skip-changelog

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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