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/src/core/task_manager/context.py

@@ -3,7 +3,7 @@
 # @PURPOSE: Provides execution context passed to plugins during task execution.
 # @LAYER: Core
 # @RELATION: DEPENDS_ON -> TaskLogger, USED_BY -> plugins
-# @TIER: CRITICAL
+# @COMPLEXITY: 5
 # @INVARIANT: Each TaskContext is bound to a single task execution.
 
 # [SECTION: IMPORTS]
@@ -16,7 +16,7 @@ from ..logger import belief_scope
 # [DEF:TaskContext:Class]
 # @SEMANTICS: context, task, execution, plugin
 # @PURPOSE: A container passed to plugin.execute() providing the logger and other task-specific utilities.
-# @TIER: CRITICAL
+# @COMPLEXITY: 5
 # @INVARIANT: logger is always a valid TaskLogger instance.
 # @UX_STATE: Idle -> Active -> Complete
 #