Add Google Contacts integration and fix critical Windows issues

- Add People API integration with contact management tools (create, list, get)
- Fix OAuth flow: replace deprecated OOB with localhost callback
- Fix Ctrl+C handling with proper signal handlers for graceful shutdown
- Fix UTF-8 encoding in scheduled_tasks.py for Windows compatibility
- Add users/ directory to gitignore to protect personal data

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

.gitignore

@@ -50,6 +50,9 @@ memory_workspace/memory_index.db
 memory_workspace/users/*.md  # User profiles (jordan.md, etc.)
 memory_workspace/vectors.usearch
 
+# User profiles (personal info)
+users/
+
 # Usage tracking
 usage_data.json