Embed the Composio key in the app bundle instead of shipping cred.txt

Root cause of the recurring 401: a revoked key was hardcoded in
startup-recovery.ts and onboarding-service.ts and reseeded into
composio_settings on every launch, and the interim fix shipped cred.txt
as a visible file under resources/.

- electron.vite.config.ts reads the gitignored cred.txt at build time
  and injects the key into the main-process bundle as
  __COMPOSIO_API_KEY__; no credential file is packaged and the key is
  not user-visible or configurable. The renderer bundle never sees it.
- Delete both hardcoded-key seeders; migration 046 purges stored
  api_key and never-read toolkits rows while keeping entity_id and
  auth_config state.
- Stop shipping composio_settings in the renderer snapshot.

src/main/database/schema.ts

@@ -44,6 +44,7 @@ import { approvalNotesMeetingsSprintsSchema } from "./migrations/042-approval-no
 import { composioIntegrationSchema } from "./migrations/043-composio-integration";
 import { mentionWakeStateSchema } from "./migrations/044-mention-wake-state";
 import { connectorGrantsSchema } from "./migrations/045-connector-grants";
+import { composioKeyPurgeSchema } from "./migrations/046-composio-key-purge";
 
 interface Migration {
   version: number;
@@ -97,6 +98,7 @@ const MIGRATIONS: Migration[] = [
   { version: 43, name: "composio_integration", sql: composioIntegrationSchema },
   { version: 44, name: "mention_wake_state", sql: mentionWakeStateSchema },
   { version: 45, name: "connector_grants", sql: connectorGrantsSchema },
+  { version: 46, name: "composio_key_purge", sql: composioKeyPurgeSchema },
 ];
 
 const SCHEMA_VERSION = MIGRATIONS[MIGRATIONS.length - 1].version;