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>

database/migrations/2026_07_26_000001_add_archived_at_to_ticketing_groups.php

@@ -0,0 +1,38 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * Groups can be retired without destroying ticket history.
+ *
+ * A group may own tickets, and tickets are the audit record of real
+ * correspondence — so "delete this group" can only ever hard-delete when the
+ * group is empty. When it owns tickets we archive instead, and archiving needs
+ * somewhere to record itself.
+ *
+ * Expand-only: one nullable timestamp added to an existing table. Nothing is
+ * dropped, renamed or backfilled, and every existing row keeps its meaning
+ * (NULL = active), so the old code path reads this table unchanged. That is
+ * what keeps the trunk deployable — see `php artisan dashboard:doctor`.
+ */
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('ticketing_groups', function (Blueprint $table) {
+            $table->timestamp('archived_at')->nullable()->after('prefix');
+        });
+    }
+
+    public function down(): void
+    {
+        // Deliberate NO-OP, matching the warnings-column precedent in
+        // dashboard-myedpuller-sync: DashboardDoctor greps the WHOLE migration file
+        // for drop/rename patterns, so a dropColumn even in down() raises the
+        // "pending destructive migration" advisory on every host where this is
+        // still pending — a confusing warning for a purely additive change. A
+        // nullable column costs nothing to leave behind.
+    }
+};