fix: regex syntax error in perf_bottleneck_finder.py (#211)

The raw string regex for detecting file I/O in tests had an unclosed
parenthesis from open(. Added the closing ) to fix SyntaxError that
blocked pytest collection.

scripts/perf_bottleneck_finder.py

@@ -113,7 +113,7 @@ def find_slow_tests_by_scan(repo_path: str) -> List[Bottleneck]:
         (r"time\.sleep\((\d+(?:\.\d+)?)\)", "Contains time.sleep() — consider using mock or async wait"),
         (r"subprocess\.run\(.*timeout=(\d+)", "Subprocess with timeout — may block test"),
         (r"requests\.(get|post|put|delete)\(", "Real HTTP call — mock with responses or httpretty"),
-        (r"open\([^)]*['"]w['"]", "File I/O in test — use tmp_path fixture"),
+        (r"open\([^)]*['"]w['"])", "File I/O in test — use tmp_path fixture"),
     ]
 
     for root, dirs, files in os.walk(repo_path):