Ticketing groups can be retired (e2e dashboard-ticketing#7)

There was no destroy route at all — only settings.groups.store and .update — so
the e2e CRUD spec, which creates an ephemeral group as its documented setup step,
could never clean up (a DELETE-spoofed POST returned 405). Every sweep left litter
behind, and an operator who mistyped a group was stuck with it forever.

Deleting a group cannot be unconditional: tickets are the audit record of real
correspondence, and tickets.group_id is a RESTRICT FK. So destroyGroup counts the
tickets and picks:

  0 tickets  -> real delete (agent access / projects / email connections are
                cascadeOnDelete, so nothing dangles). This is the teardown and
                undo-a-typo path.
  >=1 ticket -> archived_at = now(). Tickets untouched and still readable.

The caller is TOLD which happened rather than inferring it from a 302: an
expectsJson caller gets {"outcome":"deleted"|"archived","ticket_count":N}, the UI
gets distinct flash wording, and the confirm modal says which it will be BEFORE
you click ("This group has 1 ticket and will be archived, not deleted").
Archiving is idempotent; restore is a separate route.

Archived groups leave the PICKERS but nothing else: index() and create() use
scopeActive, store() validation adds whereNull('archived_at') so a stale id cannot
bypass the picker, and update() rejects transfers INTO an archived group while
always allowing the ticket's own group — otherwise a ticket stranded in an
archived group would become uneditable. Index.vue re-adds that own group to the
transfer select labelled "(archived)" so the select is never blank. Deliberately
NOT filtered: the Settings groups list (archived rows show a badge + Restore), and
agentGroupIds()/isAgent()/isManager(), which read ticketing_agent_access — so
existing agents keep working the tickets that remain. No global scope; exclusion
is per call site.

Gating is byte-identical to updateGroup: inside the existing
permission:ticketing.settings group plus requireManagerAccess(), so a super admin
with no manager row on that group is still refused (asserted).

Migration is additive — one nullable timestamp. down() is a deliberate NO-OP,
matching the myedpuller-sync warnings-column precedent: DashboardDoctor greps the
whole file for drop/rename patterns, so a dropColumn even in down() would raise a
"pending destructive migration" advisory on every host where it is still pending,
which is a confusing warning for a purely additive change. Verified against
doctor's exact regex, not a looser grep.

Tests: 9 (69 assertions). 10 mutations, all 10 detected — including forcing a hard
delete on a group with tickets, which throws a QueryException from the RESTRICT FK,
i.e. the database backs up the application check.

Browser-verified on dev: the confirm modal wording for both cases, the ARCHIVED
badge and Restore, the archived group vanishing from both the create picker and the
All-Tickets switcher while its ticket stays listed, and ZERO native
confirm/alert dialogs. doctor exit 0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/routes/ticketing.php

@@ -33,6 +33,8 @@ Route::middleware(['web', 'auth', 'app.access:ticketing'])
                 ->where('tab', 'groups|agents|priorities|statuses|projects|automation')->name('settings.tab');
             Route::post('/settings/groups',                  [TicketingSettingsController::class, 'storeGroup'])          ->name('settings.groups.store');
             Route::put('/settings/groups/{group}',           [TicketingSettingsController::class, 'updateGroup'])         ->name('settings.groups.update');
+            Route::delete('/settings/groups/{group}',        [TicketingSettingsController::class, 'destroyGroup'])        ->name('settings.groups.destroy');
+            Route::post('/settings/groups/{group}/restore',  [TicketingSettingsController::class, 'restoreGroup'])        ->name('settings.groups.restore');
             Route::post('/settings/agents',                  [TicketingSettingsController::class, 'storeAgent'])          ->name('settings.agents.store');
             Route::delete('/settings/agents/{access}',       [TicketingSettingsController::class, 'destroyAgent'])        ->name('settings.agents.destroy');
             Route::post('/settings/priorities',              [TicketingSettingsController::class, 'storePriority'])       ->name('settings.priorities.store');