Add Vitest test suite with React Testing Library

- Tests cover: app rendering, routing, API client exports
- Uses happy-dom for browser environment
- CI updated to run tests before build
- Add test scripts to package.json

Author: rolandfarkasCOM

.github/workflows/ci.yml

@@ -19,5 +19,7 @@ jobs:
       - run: npm ci
       - name: TypeScript check
         run: npm run typecheck
+      - name: Tests
+        run: npm test
       - name: Build
         run: npm run build

.gitignore

@@ -33,3 +33,8 @@ Thumbs.db
 # Logs
 *.log
 npm-debug.log*
+
+# Claude Code project files
+CLAUDE.md
+.claude/
+tasks/