feat: Wahab demo prep — Cancelled status, phone persistence, admin delete, users picker, detail-page fixes

- Add Cancelled as terminal status reachable from all active states; exclude
  from SLA breach reporting and dashboard active counts; add to status pickers
- Persist customer phone on ticket create/update (was silently dropped);
  add tickets.phone migration + legacy self-heal guard
- Add admin-only DELETE /api/tickets/{id} (removes timeline/photos/escalations)
- Add GET /api/auth/users for the assign-technician dropdown (was hardcoded)
- TicketOut now returns nested unit/category so the detail page stops showing
  '—' for Unit/Property/Category
- Ticket numbering uses max+1 so deletions never re-issue a number
- New-issue form: require Category and (standard mode) Priority client-side
- Tests: 11 new cases covering cancellation, SLA exemption, phone, delete,
  users endpoint, numbering

app/main.py

@@ -28,6 +28,16 @@ async def ensure_legacy_schema(conn) -> None:
             text("ALTER TABLE categories ADD COLUMN show_in_form BOOLEAN NOT NULL DEFAULT 1")
         )
         logger.info("Added missing categories.show_in_form column (legacy database)")
+
+    result = await conn.execute(text("SELECT name FROM sqlite_master WHERE type='table' AND name='tickets'"))
+    if result.scalar():
+        result = await conn.execute(text("PRAGMA table_info(tickets)"))
+        ticket_columns = {row[1] for row in result}
+        if "phone" not in ticket_columns:
+            await conn.execute(
+                text("ALTER TABLE tickets ADD COLUMN phone VARCHAR(50)")
+            )
+            logger.info("Added missing tickets.phone column (legacy database)")
     result = await conn.execute(
         text(
             "UPDATE categories SET name = 'Missing Item' "