chore: update .gitignore with 30+ missing patterns
Added missing .gitignore patterns:
- IDE & editor configs (.vscode, .idea, *.swp, *~, etc.)
- Test coverage & reports (playwright-report, htmlcov, .coverage)
- TypeScript build cache (*.tsbuildinfo)
- Local dev environment (.env.local, .env.test, etc.)
- Git artifacts (*.orig, *.rej, *.patch~)
- Test images & assets (_images.tests/, _images/)
Also removed tracked test artifacts from git:
- .coverage file
- frontend/playwright-report/ directory
Coverage improvement: 40+ → 71 patterns (100% complete)