Refactor: Clean up obsolete files and organize codebase structure

This commit removes deprecated modules and reorganizes code into logical directories:

Deleted files (superseded by newer systems):
- claude_code_server.py (replaced by agent-sdk direct integration)
- heartbeat.py (superseded by scheduled_tasks.py)
- pulse_brain.py (unused in production)
- config/pulse_brain_config.py (obsolete config)

Created directory structure:
- examples/ (7 example files: example_*.py, demo_*.py)
- tests/ (5 test files: test_*.py)

Updated imports:
- agent.py: Removed heartbeat module and all enable_heartbeat logic
- bot_runner.py: Removed heartbeat parameter from Agent initialization
- llm_interface.py: Updated deprecated claude_code_server message

Preserved essential files:
- hooks.py (for future use)
- adapters/skill_integration.py (for future use)
- All Google integration tools (Gmail, Calendar, Contacts)
- GLM provider code (backward compatibility)

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

requirements.txt

@@ -23,3 +23,8 @@ google-auth>=2.23.0
 google-auth-oauthlib>=1.1.0
 google-auth-httplib2>=0.1.1
 google-api-python-client>=2.108.0
+
+# Claude Agent SDK (uses Pro subscription instead of API tokens)
+claude-agent-sdk>=0.1.0
+anyio>=4.0.0
+python-dotenv>=1.0.0