feat(connectors): show and select personal AI account defaults (#19845)

Show a crown on each saved personal AI provider default. Add a provider-specific menu action to other eligible accounts. Share saved-state queries, block duplicate writes, and keep the saved crown until a write succeeds.

Keep account details available for accessible grants. Show session lookup errors with Retry. Resolve list permissions once per request and index account lookups. Add UI and API regression coverage and account documentation.

Co-Authored-By: Paperclip <noreply@paperclip.ing>
Co-Authored-By: Paperclip <Paperclip-Paperclip@users.noreply.github.com>

packages/shared/src/ai-connections.ts

@@ -186,6 +186,7 @@ export interface AiManagedConnectionSummary {
   ownerUserId?: string;
   ownerName?: string;
   isDefault: boolean;
+  canSetDefault?: boolean;
   status: "connected" | "needs_attention" | "expired" | "revoked";
   unavailableReason?: string;
   usageProbeSupported?: boolean;