Add statuses

feat: add issue status workflow and move widget into user menu

Adds Investigating, Implementing, and Pending statuses with per-status
actions that notify the issue author via a new StatusUpdate mailable.
Relocates the quick-issue widget from the floating bottom-right tab
into the Filament user profile dropdown via USER_MENU_BEFORE render
hook.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>