Refactor release workflow with separated grammar builds (#3)

* Refactor release workflow with separated grammar builds

- Replace monolithic release.yml with staged workflow:
  - Stage 1: Build grammars per platform (parallel)
  - Stage 2: Build Go binaries + create archives (parallel)
  - Stage 3: Publish release + update Homebrew/Scoop

- Add scripts/build-grammars.sh for reusable grammar compilation
- Remove release.sh (functionality now in GitHub Actions)
- Use environment variables for GitHub Actions security

Benefits:
- Clearer separation of concerns
- Easier debugging when builds fail
- Reusable grammar build script for local dev
- ~140 fewer lines of YAML

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Simplify workflow: combine grammar + Go builds into single jobs

No more intermediate artifacts - each platform job builds grammars,
Go binary, and creates the final archive in one go.

- 5 parallel build jobs (darwin x2, linux x2, windows)
- Only final archives uploaded as artifacts
- No cleanup needed
- Simpler flow, easier to debug

* Add one-click release with version bump dropdown

- Add 'bump' dropdown: none, minor, major
- Minor: v2.9 → v2.10 (no reset at 10)
- Major: v2.9 → v3.0
- Bump job creates/pushes tag, triggering full release
- Build jobs skip when bump selected (tag push handles it)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Switch to semantic versioning (MAJOR.MINOR.PATCH)

- patch: v2.1.3 → v2.1.4 (bug fixes)
- minor: v2.1.3 → v2.2.0 (new features)
- major: v2.1.3 → v3.0.0 (breaking changes)
- Handles existing 2-part tags (v2.0 → v2.0.0)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

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Co-authored-by: Claude <noreply@anthropic.com>

Author: JordanCoin