Fix garbled IPA detection for bracket-notation like [n, nn] and [1uedtX,1]

- Detect bracketed text without real IPA symbols as garbled OCR phonetics
- Allow IPA continuation fix even when other columns have content (for rows
  where EN cell is clearly garbled bracketed IPA)
- Strip parenthetical grammar annotations like (no pl) from headword before
  IPA lookup in fix_ipa_continuation_cell

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

klausur-service/backend/tests/test_grid_editor_api.py

@@ -19,6 +19,7 @@ from grid_editor_api import (
     _detect_header_rows,
     _detect_heading_rows_by_color,
 )
+from cv_ocr_engines import _text_has_garbled_ipa, fix_ipa_continuation_cell
 
 
 # ---------------------------------------------------------------------------
@@ -452,3 +453,44 @@ class TestDetectHeaderRowsSkipFlag:
         ]
         headers = _detect_header_rows(rows, words, 0, skip_first_row_header=True)
         assert 0 not in headers
+
+
+# ---------------------------------------------------------------------------
+# _text_has_garbled_ipa + fix_ipa_continuation_cell
+# ---------------------------------------------------------------------------
+
+class TestGarbledIpaDetection:
+    """Test detection and fixing of garbled IPA in bracket notation."""
+
+    def test_bracket_garbled_no_ipa_chars(self):
+        """'[n, nn]' — brackets with no real IPA chars → garbled."""
+        assert _text_has_garbled_ipa("[n, nn]") is True
+
+    def test_bracket_garbled_alphanumeric(self):
+        """'[1uedtX,1]' — brackets with digits/letters → garbled."""
+        assert _text_has_garbled_ipa("[1uedtX,1]") is True
+
+    def test_bracket_valid_ipa_not_garbled(self):
+        """'[ɪkwˈɪpmənt]' — brackets with real IPA → not garbled."""
+        assert _text_has_garbled_ipa("[ɪkwˈɪpmənt]") is False
+
+    def test_no_brackets_normal_word(self):
+        """'equipment' — normal word → not garbled."""
+        assert _text_has_garbled_ipa("equipment") is False
+
+    def test_fix_continuation_united_kingdom(self):
+        """IPA continuation for 'the United Kingdom' → proper IPA."""
+        fixed = fix_ipa_continuation_cell(
+            "[n, nn]", "the United Kingdom", pronunciation="british",
+        )
+        # Should contain proper IPA, not the garbled text
+        assert fixed != "[n, nn]"
+        assert "kˈɪŋdəm" in fixed  # Kingdom IPA
+
+    def test_fix_continuation_equipment(self):
+        """IPA continuation for 'equipment' → proper IPA."""
+        fixed = fix_ipa_continuation_cell(
+            "[1uedtX,1]", "equipment (no pl)", pronunciation="british",
+        )
+        assert fixed != "[1uedtX,1]"
+        assert "ɪkwˈɪpmənt" in fixed  # equipment IPA