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

frontend/src/lib/components/assistant/AssistantChatPanel.svelte

@@ -1,7 +1,7 @@
 <!-- [DEF:AssistantChatPanel:Component] -->
 <script>
   /**
-   * @TIER: CRITICAL
+   * @COMPLEXITY: 5
    * @PURPOSE: Slide-out assistant chat panel for natural language command execution and task tracking.
    * @LAYER: UI
    * @RELATION: BINDS_TO -> assistantChatStore

frontend/src/lib/components/assistant/__tests__/assistant_chat.integration.test.js

@@ -1,5 +1,5 @@
 // [DEF:frontend.src.lib.components.assistant.__tests__.assistant_chat_integration:Module]
-// @TIER: STANDARD
+// @COMPLEXITY: 3
 // @SEMANTICS: assistant, integration-test, ux-contract, i18n
 // @PURPOSE: Contract-level integration checks for assistant chat panel implementation and localization wiring.
 // @LAYER: UI Tests

frontend/src/lib/components/assistant/__tests__/assistant_first_message.integration.test.js

@@ -1,5 +1,5 @@
 // [DEF:frontend.src.lib.components.assistant.__tests__.assistant_first_message_integration:Module]
-// @TIER: STANDARD
+// @COMPLEXITY: 3
 // @SEMANTICS: assistant, integration-test, optimistic-message, conversation-race
 // @PURPOSE: Verify first optimistic user message stays visible while a new conversation request is pending.
 // @LAYER: UI Tests
@@ -121,7 +121,7 @@ vi.mock('$lib/i18n', () => ({
 }));
 
 // [DEF:assistant_first_message_tests:Function]
-// @TIER: STANDARD
+// @COMPLEXITY: 3
 // @PURPOSE: Guard optimistic first-message UX against history reload race in new conversation flow.
 // @PRE: Assistant panel renders with open state and mocked network dependencies.
 // @POST: First user message remains visible before pending send request resolves.