refactor(semantics): migrate legacy @TIER to @COMPLEXITY annotations

- Replaced @TIER: TRIVIAL with @COMPLEXITY: 1
- Replaced @TIER: STANDARD with @COMPLEXITY: 3
- Replaced @TIER: CRITICAL with @COMPLEXITY: 5
- Manually elevated specific critical/complex components to levels 2 and 4
- Ignored legacy, specs, and node_modules directories
- Updated generated semantic map

backend/tests/test_log_persistence.py

@@ -3,7 +3,7 @@
 # @PURPOSE: Unit tests for TaskLogPersistenceService.
 # @LAYER: Test
 # @RELATION: TESTS -> TaskLogPersistenceService
-# @TIER: CRITICAL
+# @COMPLEXITY: 5
 
 # [SECTION: IMPORTS]
 from datetime import datetime
@@ -19,7 +19,7 @@ from src.core.task_manager.models import LogEntry, LogFilter
 
 # [DEF:TestLogPersistence:Class]
 # @PURPOSE: Test suite for TaskLogPersistenceService.
-# @TIER: CRITICAL
+# @COMPLEXITY: 5
 # @TEST_DATA: log_entry -> {"task_id": "test-task-1", "level": "INFO", "source": "test_source", "message": "Test message"}
 class TestLogPersistence: