Add `extract_pattern` utility function to support regex-based string extraction in `gaia_solving_agent`

src/gaia_solving_agent/utils.py

@@ -0,0 +1,7 @@
+import re
+
+
+def extract_pattern(pattern: str, text: str) -> str:
+    search = re.search(pattern, text)
+    extracted = search.group(1) if search else ""
+    return extracted