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/plugin.py

@@ -1,15 +1,17 @@
-# #region TranslatePlugin [C:3] [TYPE Module] [SEMANTICS plugin,translate,llm,sql,dashboard]
+# #region TranslatePlugin [C:2] [TYPE Module] [SEMANTICS plugin, translate, llm, sql, dashboard]
 # @BRIEF TranslatePlugin skeleton for cross-dialect SQL and dashboard translation.
-# @LAYER Domain
+# @LAYER: Domain
 # @RELATION INHERITS -> [PluginBase]
+# @RATIONALE: Separate plugin avoids bloating LLMAnalysisPlugin beyond fractal limit (<400 lines).
+# @REJECTED: Extending LLMAnalysisPlugin would conflate two distinct feature domains.
 
 from typing import Dict, Any, Optional
 from ...core.plugin_base import PluginBase
 
 
-# #region TranslatePlugin [C:3] [TYPE Class] [SEMANTICS plugin,translate]
+# #region TranslatePlugin [TYPE Class]
 # @BRIEF Plugin for translating SQL queries and dashboard definitions across database dialects.
-# @RELATION IMPLEMENTS -> [PluginBase]
+# @RELATION IMPLEMENTS -> backend.src.core.plugin_base.PluginBase
 class TranslatePlugin(PluginBase):
     @property
     def id(self) -> str: