fix(arch): unify TS/Rust types + classroom persistence registration + approval audit

- M11-03: Register ClassroomPersistence via Tauri .setup() hook with
  in-memory fallback. Previously missing — classroom commands would crash at runtime.
- M3-02: Document BrowserHand as schema validator + TypeScript delegation
  passthrough (dual-path architecture explicitly documented).
- M4-04: Add defense-in-depth audit logging in execute_hand() and
  execute_hand_with_source() when needs_approval hands bypass approval gate.
- TYPE-01: Add #[serde(rename_all = "camelCase")] to Rust AgentInfo.
  Add missing fields to TS AgentInfo (messageCount, createdAt, updatedAt).
  Fix KernelStatus TS interface to match Rust KernelStatusResponse
  (baseUrl/model instead of defaultProvider/defaultModel).
- SEC2-P1-01: Document EXTRACTION_DRIVER OnceCell as legacy path;
  Kernel struct field is the active path.
- TriggerSource: Add #[derive(PartialEq)] for approval audit comparisons.

desktop/src/lib/kernel-client.ts

@@ -275,8 +275,8 @@ export class KernelClient {
     return {
       initialized: status.initialized,
       agentCount: status.agentCount,
-      defaultProvider: status.defaultProvider,
-      defaultModel: status.defaultModel,
+      defaultProvider: status.baseUrl,
+      defaultModel: status.model,
     };
   }