docs: Merge debugging tools into OBSERVABILITY.md

Consolidated CLI debugging scripts documentation into the existing
OBSERVABILITY.md rather than creating a separate file.

Added "CLI Debugging Scripts" section covering:
- Connection & WebSocket debugging (monitor-connections, analyze-ws-storm)
- State & hash debugging (debug-state-hash, compare-sessions)
- Session inspection (debug-session, debug-metrics)
- Testing utilities (create-test-sessions, trigger-state-changes)
- Bug analysis (analyze-bug-patterns)

Deleted redundant DEVELOPMENT-TOOLS.md to avoid documentation sprawl.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: adewale