feat(memory): implement MCP tools for agent memory operations (#96)

Add MCP-compatible tools that expose memory operations to agents:

Tools implemented:
- remember: Store data in working, episodic, semantic, or procedural memory
- recall: Retrieve memories by query across multiple memory types
- forget: Delete specific keys or bulk delete by pattern
- reflect: Analyze patterns in recent episodes (success/failure factors)
- get_memory_stats: Return usage statistics and breakdowns
- search_procedures: Find procedures matching trigger patterns
- record_outcome: Record task outcomes and update procedure success rates

Key components:
- tools.py: Pydantic schemas for tool argument validation with comprehensive
  field constraints (importance 0-1, TTL limits, limit ranges)
- service.py: MemoryToolService coordinating memory type operations with
  proper scoping via ToolContext (project_id, agent_instance_id, session_id)
- Lazy initialization of memory services (WorkingMemory, EpisodicMemory,
  SemanticMemory, ProceduralMemory)

Test coverage:
- 60 tests covering tool definitions, argument validation, and service
  execution paths
- Mock-based tests for all memory type interactions

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

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

backend/app/services/memory/__init__.py

@@ -133,4 +133,6 @@ __all__ = [
     "get_default_settings",
     "get_memory_settings",
     "reset_memory_settings",
+    # MCP Tools - lazy import to avoid circular dependencies
+    # Import directly: from app.services.memory.mcp import MemoryToolService
 ]