fix: comprehensive quality improvements

- Fix 2 backend test failures (projectFolders validation, StressTest timeout)
- Fix frontend test dependency (@testing-library/dom)
- Delete App.tsx.bak from repo
- Add rate limiting on auth endpoints (login: 10/min, register: 3/min)
- Add .env.example with all environment variables
- Update BAUPLAN.md with accurate phase status (16/21 phases implemented)
- Add OpenAPI/Swagger documentation (docs/openapi.yaml)
- Add E2E workflow test (15 steps: register→project→drawing→layer→element→CRUD→delete)
- Add Forgejo CI/CD pipeline (.forgejo/workflows/ci.yml)
- Improve .gitignore (db-wal, .env.*, *.bak, coverage)
- Add security comment for default user in schema.sql

All 628 tests passing (254 backend + 374 frontend)

.forgejo/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  backend-test:
+    runs-on: docker
+    container: node:20
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install backend dependencies
+        working-directory: backend
+        run: npm ci --legacy-peer-deps || npm install --legacy-peer-deps
+      - name: Run backend tests
+        working-directory: backend
+        run: npm test
+      - name: Build backend
+        working-directory: backend
+        run: npm run build
+
+  frontend-test:
+    runs-on: docker
+    container: node:20
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install frontend dependencies
+        working-directory: frontend
+        run: npm ci --legacy-peer-deps || npm install --legacy-peer-deps
+      - name: Run frontend tests
+        working-directory: frontend
+        run: npm test
+      - name: Build frontend
+        working-directory: frontend
+        run: npm run build