feat: add The Housekeeper agent for home automation

Implements The Housekeeper, a new expert agent for home automation
following the Librarian pattern. Communicates with core-api service
which wraps Home Assistant REST API.

New agent features:
- CoreAPIClient with 13 home automation methods
- 13 tools: list_areas, list_devices, get_device_state, turn_on,
  turn_off, toggle, list_scenes, activate_scene, list_scripts,
  run_script, list_automations, toggle_automation, get_history
- PydanticAI agent with butler-friendly system prompt
- HouseholdCapability registration for Steward coordination
- delegate_to_housekeeper() wrapper for orchestration

Also includes:
- Dev port changed from 8123 to 8777 (avoids Home Assistant conflict)
- Config: CORE_API_HOST, CORE_API_KEY, CORE_API_TIMEOUT
- 44 unit tests for client and capability

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

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

.env.example

@@ -42,5 +42,15 @@ ENABLE_BENCHMARKS=true
 #   - production: jpmschweitzer (real user)
 # Uncomment to override: DEFAULT_USER=your_username
 
+# Library-Desk Configuration (The Librarian backend)
+# LIBRARY_DESK_HOST=http://localhost:8089
+# LIBRARY_DESK_API_KEY=your-library-desk-api-key
+# LIBRARY_DESK_TIMEOUT=60
+
+# Core-API Configuration (The Housekeeper backend)
+# CORE_API_HOST=http://localhost:8090
+# CORE_API_KEY=your-core-api-key
+# CORE_API_TIMEOUT=30
+
 # CORS (comma-separated list)
 CORS_ORIGINS=["*"]