Add complete X (Twitter) integration with Letta agent support
## Core X Integration Features
- **X API Client**: Full X API v2 integration with OAuth 1.0a support
- **Queue System**: Fetch mentions and process separately for rate limit management
- **Thread Context**: Convert X conversations to YAML for agent comprehension
- **User Block Management**: X-specific user blocks with format `x_user_<user_id>`
## X Tool System
- **register_x_tools.py**: X-specific tool registration following Bluesky patterns
- **tools/x_thread.py**: X thread tool with 280 character limit validation
- **X_TOOL_APPROACH.md**: Documentation explaining tool-as-signal pattern
## Bot Functionality
- **process_x_mention()**: Complete X mention processing with Letta agent integration
- **X Reply Handling**: Thread construction and posting with proper reply chaining
- **Acknowledgment System**: X post acknowledgment tracking (file-based)
- **Testing Mode**: Safe testing without actual X posts
## Manual Queue Management
- `python x.py queue` - Fetch mentions only (rate limit safe)
- `python x.py process` - Process queued mentions only
- `python x.py bot` - Full bot loop (like bsky.py)
## Configuration Fix
- **config_loader.py**: Fixed to use config.yaml only, ignore environment variables
## Key Differences from Bluesky
- Character limit: 280 vs 300
- User identification: Numeric IDs vs handles
- Block format: `x_user_<user_id>` vs `user_<handle>`
- Acknowledgments: File-based vs stream.thought.ack API
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>