refactor: migrate data storage from JSON/map files to SQLite

Replace servers.json, certificates.json, and map file parsing with
SQLite (WAL mode) as single source of truth. HAProxy map files are
now generated from SQLite via sync_map_files().

Key changes:
- Add db.py with schema, connection management, and JSON migration
- Add DB_FILE config constant
- Delegate file_ops.py functions to db.py
- Refactor domains.py to use file_ops instead of direct list manipulation
- Fix subprocess.TimeoutExpired not caught (doesn't inherit TimeoutError)
- Add DB health check in health.py
- Init DB on startup in server.py and __main__.py
- Update all 359 tests to use SQLite-backed functions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

haproxy_mcp/tools/configuration.py

@@ -1,5 +1,6 @@
 """Configuration management tools for HAProxy MCP Server."""
 
+import subprocess
 import time
 
 from ..config import (
@@ -177,7 +178,7 @@ def register_config_tools(mcp):
             if result.returncode == 0:
                 return "Configuration is valid"
             return f"Configuration errors:\n{result.stderr}"
-        except TimeoutError:
+        except (TimeoutError, subprocess.TimeoutExpired):
             return f"Error: Command timed out after {SUBPROCESS_TIMEOUT} seconds"
         except FileNotFoundError:
             return "Error: ssh/podman command not found"