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/Models/TicketingGroup.php

@@ -2,6 +2,7 @@
 
 namespace Dashboard\Ticketing\Models;
 
+use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 
@@ -9,6 +10,36 @@ class TicketingGroup extends Model
 {
     protected $fillable = ['name', 'email_address', 'color', 'prefix'];
 
+    protected $casts = [
+        'archived_at' => 'datetime',
+    ];
+
+    protected $appends = ['is_archived'];
+
+    /**
+     * Archived groups are deliberately NOT hidden by a global scope.
+     *
+     * The tickets in an archived group are still live correspondence: their
+     * agents must keep working them, `$ticket->group` must still resolve, and
+     * Settings must still list the group so a manager can restore it. Only the
+     * *pickers* — "which group should this new ticket go to", "filter by
+     * group" — exclude archived ones, via this scope, one call site at a time.
+     */
+    public function scopeActive(Builder $query): Builder
+    {
+        return $query->whereNull('archived_at');
+    }
+
+    public function scopeArchived(Builder $query): Builder
+    {
+        return $query->whereNotNull('archived_at');
+    }
+
+    public function getIsArchivedAttribute(): bool
+    {
+        return $this->archived_at !== null;
+    }
+
     public function tickets(): HasMany
     {
         return $this->hasMany(Ticket::class, 'group_id');