Add MCP delegation bridge and diagram tools

**Features Added**:

1. **Agent Registry (agent_registry.py)**
   - Thread-safe global singleton for MCP tool access to Agent instance
   - Enables MCP tools to call Agent.delegate() without circular imports
   - Registered at bot startup in bot_runner.py

2. **Sub-Agent Manager (sub_agent_manager.py)**
   - Watchdog system monitoring sub-agent lifecycle
   - Detects hung agents (5min timeout, 30s check interval)
   - Auto-cleanup and status tracking

3. **delegate_task MCP Tool (mcp_tools.py)**
   - Exposes Agent.delegate() to Claude via MCP protocol
   - Enables parallel sub-agent execution via tool calls
   - Supports specialist prompts and agent ID caching

4. **Memory Write Locks (memory_system.py)**
   - Thread-safe writes to prevent file corruption
   - Protects write_memory(), update_soul(), update_user()

5. **Diagram Tools**
   - Mermaid MCP server (flowcharts, sequence diagrams, etc.)
   - Excalidraw MCP server (hand-drawn style diagrams)
   - Config files in config/ directory

6. **Adapter Improvements**
   - Enhanced error handling across all adapters
   - Unified logging patterns

**Testing**: Ready for parallel sub-agent testing

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

mcp_servers/mermaid/mermaid_mcp.py

@@ -0,0 +1,86 @@
+"""Mermaid MCP Server Integration.
+
+Manages the external @peng-shawn/mermaid-mcp-server process for diagram generation.
+
+Architecture:
+    Garvis → (stdio) → mermaid-mcp-server (Node.js) → Puppeteer → PNG images
+"""
+
+import os
+from pathlib import Path
+from typing import Any, Dict, List
+import yaml
+
+_CONFIG_FILE = Path("config/mermaid_mcp.yaml")
+
+def _load_config() -> Dict[str, Any]:
+    """Load Mermaid MCP configuration from YAML and env vars."""
+    config = {}
+    if _CONFIG_FILE.exists():
+        try:
+            with open(_CONFIG_FILE, encoding="utf-8") as f:
+                config = yaml.safe_load(f) or {}
+        except Exception:
+            pass  # Use defaults if config fails to load
+
+    mermaid = config.get("mermaid_mcp", {})
+
+    # Apply env var overrides
+    if os.getenv("MERMAID_ENABLED"):
+        mermaid["enabled"] = os.getenv("MERMAID_ENABLED").lower() in ("true", "1")
+    if os.getenv("MERMAID_OUTPUT_DIR"):
+        mermaid["output_dir"] = os.getenv("MERMAID_OUTPUT_DIR")
+    if os.getenv("MERMAID_DEFAULT_FORMAT"):
+        mermaid["default_format"] = os.getenv("MERMAID_DEFAULT_FORMAT")
+    if os.getenv("MERMAID_THEME"):
+        mermaid["theme"] = os.getenv("MERMAID_THEME")
+
+    # Set defaults if not configured
+    mermaid.setdefault("enabled", True)
+    mermaid.setdefault("output_dir", "downloads/diagrams/mermaid")
+    mermaid.setdefault("default_format", "png")
+    mermaid.setdefault("theme", "default")
+
+    return mermaid
+
+def is_mermaid_enabled() -> bool:
+    """Check if Mermaid MCP integration is enabled."""
+    config = _load_config()
+    return config.get("enabled", True)
+
+def get_mermaid_server_config() -> Dict[str, Any]:
+    """Build the MCP server configuration for Agent SDK registration.
+
+    Returns:
+        Dict with command, args, and env for subprocess execution
+    """
+    config = _load_config()
+    output_dir = config.get("output_dir", "downloads/diagrams/mermaid")
+
+    # Ensure output directory exists
+    Path(output_dir).mkdir(parents=True, exist_ok=True)
+
+    # Build environment variables for the MCP server
+    env = {
+        "PATH": os.environ.get("PATH", ""),
+        "HOME": os.environ.get("HOME", os.environ.get("USERPROFILE", "")),
+        "APPDATA": os.environ.get("APPDATA", ""),
+        "TEMP": os.environ.get("TEMP", os.environ.get("TMP", "")),
+    }
+
+    # Add config as env vars for the server
+    env["MERMAID_OUTPUT_DIR"] = str(Path(output_dir).absolute())
+    env["MERMAID_DEFAULT_FORMAT"] = config.get("default_format", "png")
+    env["MERMAID_THEME"] = config.get("theme", "default")
+
+    return {
+        "command": "npx",
+        "args": ["-y", "@peng-shawn/mermaid-mcp-server"],
+        "env": env,
+    }
+
+# Tool names exposed by mermaid-mcp-server
+# Based on @peng-shawn/mermaid-mcp-server documentation
+MERMAID_TOOLS: List[str] = [
+    "render_mermaid",  # Main tool: convert Mermaid syntax to PNG
+]