Strip English IPA when mode excludes EN (nur DE / Aus)

English IPA from the original OCR scan (e.g. [ˈgrænˌdæd]) was always
shown because fix_cell_phonetics only ADDS/CORRECTS but never removes.
Now strips IPA brackets containing Unicode IPA chars from the EN column
when ipa_mode is "de" or "none".

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

klausur-service/backend/grid_editor_api.py

@@ -1002,6 +1002,24 @@ async def _build_grid_core(
                 en_ipa_target_cols.add(en_col_type)
             de_ipa_target_cols = all_content_cols - en_ipa_target_cols
 
+        # --- Strip IPA from columns NOT in the target set ---
+        # When user selects "nur DE", English IPA from the OCR scan must
+        # be removed.  When "none", all IPA is removed.
+        _IPA_BRACKET_STRIP_RE = re.compile(r'\s*\[[^\]]*[ˈˌːɑɒæɛəɜɪɔʊʌðŋθʃʒɹɡɾʔɐ][^\]]*\]')
+        strip_en_ipa = en_col_type and en_col_type not in en_ipa_target_cols
+        if strip_en_ipa or ipa_mode == "none":
+            strip_cols = {en_col_type} if strip_en_ipa and ipa_mode != "none" else all_content_cols
+            for cell in all_cells:
+                ct = cell.get("col_type", "")
+                if ct not in strip_cols:
+                    continue
+                text = cell.get("text", "")
+                if "[" in text:
+                    stripped = _IPA_BRACKET_STRIP_RE.sub("", text)
+                    if stripped != text:
+                        cell["text"] = stripped.strip()
+                        cell["_ipa_corrected"] = True
+
         # --- English IPA (Britfone + eng_to_ipa) ---
         if en_ipa_target_cols:
             for cell in all_cells: