Creates Gitea Actions workflow that runs on pull requests and pushes
to main. Enforces quality gates (lint, typecheck, unit tests) in CI,
complementing the local Lefthook pre-commit hooks.
Features:
- Node.js 24 with pnpm 10 setup
- pnpm dependency caching for faster runs
- Linting with biome
- TypeScript type checking
- 950 unit tests via vitest
Completes P5.3 from the implementation plan.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>