refactor(workspace-settings): extract useWorkspaceSetting hook

Deduplicate the "save a workspace setting" plumbing shared by HtmlEmbedSettings
and TrackerSettings (workspace atom read, isLoading state, updateWorkspace + atom
merge forcing settings[key], success/error notifications) into a new
feature-scoped hook useWorkspaceSetting(key).

- Each component keeps its own interaction model: html-embed is an optimistic
  toggle with revert-on-failure; tracker is edit-then-save on an explicit button.
- Unify error handling on the better pattern: surface err.response?.data?.message
  and use console.error (html-embed previously used console.log + a generic message).

No user-facing behavior change; client typecheck clean.

Test-coverage follow-ups (untested trackerHead injection in ShareSeoController and
the no-op audit branch) tracked in #100.

apps/server/src/core/share/share.controller.ts

@@ -87,9 +87,16 @@ export class ShareController {
       workspace.id,
     );
 
+    // Resolve the identity name only when the assistant is enabled, so the
+    // anonymous widget can label messages with the configured persona name.
+    const aiAssistantName = aiAssistant
+      ? await this.aiSettings.resolvePublicShareAssistantName(workspace.id)
+      : null;
+
     return {
       ...shareData,
       aiAssistant,
+      aiAssistantName,
       features: this.licenseCheckService.resolveFeatures(
         workspace.licenseKey,
         workspace.plan,