feat: add "Create Spec" button and fix Windows asyncio subprocess

UI Changes:
- Add "Create Spec with AI" button in empty kanban when project has no spec
- Button opens SpecCreationChat to guide users through spec creation
- Shows in Pending column when has_spec=false and no features exist

Windows Fixes:
- Fix asyncio subprocess NotImplementedError on Windows
- Set WindowsProactorEventLoopPolicy in server/__init__.py
- Remove --reload from uvicorn (incompatible with Windows subprocess)
- Add process cleanup on startup in start_ui.bat

Spec Chat Improvements:
- Enable full tool access (remove allowed_tools restriction)
- Add "user" to setting_sources for global skills access
- Use bypassPermissions mode for auto-approval
- Add WebFetch/WebSearch auto-approve hook

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

server/main.py

@@ -6,11 +6,17 @@ Main entry point for the Autonomous Coding UI server.
 Provides REST API, WebSocket, and static file serving.
 """
 
+import asyncio
 import os
 import shutil
+import sys
 from contextlib import asynccontextmanager
 from pathlib import Path
 
+# Fix for Windows subprocess support in asyncio
+if sys.platform == "win32":
+    asyncio.set_event_loop_policy(asyncio.WindowsProactorEventLoopPolicy())
+
 from dotenv import load_dotenv
 
 # Load environment variables from .env file if present