Fix gutter repair: don't suggest corrections for words with parentheses

Words like "probieren)" or "Englisch)" were incorrectly flagged as
gutter OCR errors because the closing parenthesis wasn't stripped
before dictionary lookup. The spellchecker then suggested "probierend"
(replacing ) with d, edit distance 1).

Two fixes:
1. Strip trailing/leading parentheses in _try_spell_fix before checking
   if the bare word is valid — skip correction if it is
2. Add )( to the rstrip characters in the analysis phase so
   "probieren)" becomes "probieren" for the known-word check

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

klausur-service/backend/cv_gutter_repair.py

@@ -217,6 +217,13 @@ def _try_spell_fix(
     if len(word_text) < _MIN_WORD_LEN_SPELL:
         return None
 
+    # Strip trailing/leading parentheses and check if the bare word is valid.
+    # Words like "probieren)" or "(Englisch" are valid words with punctuation,
+    # not OCR errors. Don't suggest corrections for them.
+    stripped = word_text.strip("()")
+    if stripped and _is_known(stripped):
+        return None
+
     # Determine language priority from column type
     if "en" in col_type:
         lang = "en"
@@ -362,7 +369,7 @@ def analyse_grid_for_gutter_repair(
             if last_word.lower().rstrip(".,;:!?-") in _STOPWORDS:
                 continue
 
-            last_word_clean = last_word.rstrip(".,;:!?")
+            last_word_clean = last_word.rstrip(".,;:!?)(")
             if len(last_word_clean) < _MIN_WORD_LEN_HYPHEN:
                 continue