v0.9.10 - web toast notifications

What's changed

• Added a global Base UI toast layer for transient action feedback.
• Surfaced previously silent mutation failures for chat rename, chat move, project updates, and model toggles.
• Added success receipts for destructive/import/admin actions while preserving inline retry errors in dialogs and forms.
• Centralized user-facing error extraction for more consistent feedback.

Validation

• npm run lint -w apps/web --
• npm run test -w apps/web --
• npm run build -w apps/web --