In TicketMate-centralised mode the consuming app should not send any of
its own confirmation/transition emails — TM owns the user-facing
conversation. Until now this only held for the IssueQuickAction (the
floating Report-a-Bug modal) and the Issue::created AI listener.

Five other paths still fired Mail::to(...)->send(...) when TM was on:

- github:sync-issues cron — sent Closure / StatusUpdate / Comment
  mailables on every sync. Whole command is now a no-op in TM mode.
- IssueResource list/create/edit pages — sent Confirmation +
  "New Request Logged" Notification when issues were created via the
  Filament admin UI rather than the modal, and Closure when an admin
  closed an issue from the resource.
- CommentsRelationManager + IssueResource table actions — sent
  Comment mailers when admins added/edited comments.

Each Mail::send call site is now wrapped in
\`! TicketmateClient::isEnabled()\`, so the package degrades cleanly to
its old local-only behaviour in apps that do not have TM configured.