semantics: complete DEF-to-region migration, fix regressions

- Convert legacy [DEF🆔Type] anchors to #region/#endregion across 329 files
- Reinstate _normalize_timestamp_value in sql_generator.py
- Fix MarkerLogger→logger migration in events.py (molecular CoT markers)
- Fix dataset_review orchestrator dependencies (_build_execution_snapshot)
- Fix config_manager stale-record deletion (moved to save path only)
- Add 77 missing [/DEF:] closers in 5 unbalanced test files
- Update assistant_chat.integration.test.js for #region format
- Apply molecular-cot-logging markers (REASON/REFLECT/EXPLORE) via logger.* methods

backend/src/plugins/translate/_utils.py

@@ -1,12 +1,17 @@
-# #region DictionaryUtils [C:1] [TYPE Module]
-# #endregion DictionaryUtils
+# #region DictionaryUtils [C:1] [TYPE Module] [SEMANTICS dictionary, utils, normalize, delimiter]
+# @BRIEF Utility helpers for dictionary management (term normalization and delimiter detection).
+# @LAYER: Domain
 
 import re
 import unicodedata
 
 
-# #region _normalize_term [C:2] [TYPE Function] [SEMANTICS dictionary,normalize]
-# @BRIEF Normalize a term for case-insensitive unique constraint lookup using NFC normalization.
+# #region _normalize_term [TYPE Function]
+# @BRIEF Normalize a term for case-insensitive unique constraint lookup.
+# @RATIONALE: NFC normalization is applied before lowercasing to ensure consistent
+#             comparison of Unicode characters (e.g. precomposed vs decomposed forms).
+# @REJECTED: Lowercasing without NFC normalization — would cause duplicate entries
+#            for semantically identical Unicode strings in different normalization forms.
 def _normalize_term(term: str) -> str:
     """Normalize a term by NFC, lowercasing, and removing extra whitespace."""
     if not term:
@@ -16,7 +21,8 @@ def _normalize_term(term: str) -> str:
 # #endregion _normalize_term
 
 
-# #region _detect_delimiter [C:1] [TYPE Function] [SEMANTICS dictionary,delimiter]
+# #region _detect_delimiter [TYPE Function]
+# @BRIEF Detect the delimiter used in a CSV/TSV header line.
 def _detect_delimiter(header_line: str) -> str:
     """Detect delimiter by counting tabs vs commas in the first line."""
     if not header_line:
@@ -25,3 +31,4 @@ def _detect_delimiter(header_line: str) -> str:
     comma_count = header_line.count(",")
     return "\t" if tab_count > comma_count else ","
 # #endregion _detect_delimiter
+# #endregion DictionaryUtils