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>

agent.py

@@ -20,16 +20,14 @@ if sys.platform == "win32":
     sys.stderr = io.TextIOWrapper(sys.stderr.buffer, encoding='utf-8', errors='replace')
 
 from client import create_client
-from progress import print_session_header, print_progress_summary, has_features
+from progress import has_features, print_progress_summary, print_session_header
 from prompts import (
-    get_initializer_prompt,
+    copy_spec_to_project,
     get_coding_prompt,
     get_coding_prompt_yolo,
-    copy_spec_to_project,
-    has_project_prompts,
+    get_initializer_prompt,
 )
 
-
 # Configuration
 AUTO_CONTINUE_DELAY_SECONDS = 3