refactor: Extract large functions, improve exception handling, remove duplicates

## Large function extraction
- servers.py: Extract 8 _impl functions from register_server_tools (449 lines)
- certificates.py: Extract 7 _impl functions from register_certificate_tools (386 lines)
- MCP tool wrappers now delegate to module-level implementation functions

## Exception handling improvements
- Replace 11 broad `except Exception` with specific types
- health.py: (OSError, subprocess.SubprocessError)
- configuration.py: (HaproxyError, IOError, OSError, ValueError)
- servers.py: (IOError, OSError, ValueError)
- certificates.py: FileNotFoundError, (subprocess.SubprocessError, OSError)

## Duplicate code extraction
- Add parse_servers_state() to utils.py (replaces 4 duplicate parsers)
- Add disable_server_slot() to utils.py (replaces duplicate patterns)
- Update health.py, servers.py, domains.py to use new helpers

## Other improvements
- Add TypedDict types in file_ops.py and health.py
- Set file permissions (0o600) for sensitive files
- Update tests to use specific exception types

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

haproxy_mcp/file_ops.py

@@ -94,8 +94,8 @@ def _read_map_file(file_path: str) -> list[tuple[str, str]]:
         with open(file_path, "r", encoding="utf-8") as f:
             try:
                 fcntl.flock(f.fileno(), fcntl.LOCK_SH)
-            except OSError:
-                pass  # Continue without lock if not supported
+            except OSError as e:
+                logger.debug("File locking not supported for %s: %s", file_path, e)
             try:
                 for line in f:
                     line = line.strip()
@@ -107,10 +107,10 @@ def _read_map_file(file_path: str) -> list[tuple[str, str]]:
             finally:
                 try:
                     fcntl.flock(f.fileno(), fcntl.LOCK_UN)
-                except OSError:
-                    pass
+                except OSError as e:
+                    logger.debug("File unlock failed for %s: %s", file_path, e)
     except FileNotFoundError:
-        pass
+        logger.debug("Map file not found: %s", file_path)
     return entries
 
 
@@ -420,16 +420,16 @@ def load_certs_config() -> list[str]:
         with open(CERTS_FILE, "r", encoding="utf-8") as f:
             try:
                 fcntl.flock(f.fileno(), fcntl.LOCK_SH)
-            except OSError:
-                pass
+            except OSError as e:
+                logger.debug("File locking not supported for %s: %s", CERTS_FILE, e)
             try:
                 data = json.load(f)
                 return data.get("domains", [])
             finally:
                 try:
                     fcntl.flock(f.fileno(), fcntl.LOCK_UN)
-                except OSError:
-                    pass
+                except OSError as e:
+                    logger.debug("File unlock failed for %s: %s", CERTS_FILE, e)
     except FileNotFoundError:
         return []
     except json.JSONDecodeError as e: