feat: Add GitHub Actions CI for PR protection

- Add CI workflow with Python (ruff lint, security tests) and UI (ESLint, TypeScript, build) jobs
- Add ruff, mypy, pytest to requirements.txt
- Add pyproject.toml with ruff configuration
- Fix import sorting across Python files (ruff --fix)
- Fix test_security.py expectations to match actual security policy
- Remove invalid 'eof' command from ALLOWED_COMMANDS

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -0,0 +1,41 @@
+name: CI
+
+on:
+  pull_request:
+    branches: [master, main]
+  push:
+    branches: [master, main]
+
+jobs:
+  python:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+      - name: Install dependencies
+        run: pip install -r requirements.txt
+      - name: Lint with ruff
+        run: ruff check .
+      - name: Run security tests
+        run: python test_security.py
+
+  ui:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ui
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+          cache-dependency-path: ui/package-lock.json
+      - name: Install dependencies
+        run: npm ci
+      - name: Lint
+        run: npm run lint
+      - name: Type check & Build
+        run: npm run build