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/core/middleware/trace.py

@@ -2,8 +2,8 @@
 # @BRIEF FastAPI/Starlette middleware that seeds a trace_id for every incoming HTTP request.
 #           Optionally extracts X-Trace-ID header for cross-service trace propagation.
 # @LAYER: Core
-# @RELATION: [DEPENDS_ON] -> [CotLoggerModule]
-# @RELATION: [CALLED_BY] -> [AppModule]
+# @RELATION DEPENDS_ON -> [CotLoggerModule]
+# @RELATION CALLED_BY -> [AppModule]
 # @PRE: FastAPI app instance with Starlette middleware support.
 # @POST: Every request gets a trace_id via seed_trace_id(). Existing X-Trace-ID header is
 #        preserved and used as the trace_id when present.
@@ -68,3 +68,4 @@ class TraceContextMiddleware(BaseHTTPMiddleware):
 
 
 # #endregion TraceContextMiddleware
+# #endregion TraceContextMiddlewareModule