ruff: remove unused noqa

Most of them are actually correct, but they're not enforced in general on the repo, so using them blocks us from flagging `unused-noqa` for rules that we actually do use.

src/ifcmcp/ifcmcp/__main__.py

@@ -1,5 +1,6 @@
 # This file was generated with the assistance of an AI coding tool.
 import argparse
+import importlib.util
 
 from ifcmcp import __version__
 
@@ -27,9 +28,7 @@ def main():
 
     args = parser.parse_args()
 
-    try:
-        from mcp.server.fastmcp import FastMCP  # noqa: F401
-    except ImportError:
+    if importlib.util.find_spec("mcp.server.fastmcp") is None:
         import sys
 
         print(

src/ifcmcp/ifcmcp/core.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 
 # inside ifcmcp/core.py
 import json
-from collections.abc import Callable  # noqa: F401 — Callable used in helpers below
+from collections.abc import Callable
 from dataclasses import dataclass
 from typing import Any