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

alembic/versions/c4e8f1a2d3b4_tickets_phone_and_cancelled_status.py

@@ -0,0 +1,40 @@
+"""tickets.phone column + Cancelled status support
+
+Revision ID: c4e8f1a2d3b4
+Revises: b2f4a6c8e0d2
+Create Date: 2026-08-02 00:00:00.000000
+
+Demo-prep batch (Wahab review): one schema change.
+
+* Add ``tickets.phone`` (nullable) so the customer phone collected on the
+  new-issue form is actually persisted instead of silently dropped.
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'c4e8f1a2d3b4'
+down_revision: Union[str, Sequence[str], None] = 'b2f4a6c8e0d2'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Add tickets.phone (nullable)."""
+    op.add_column(
+        'tickets',
+        sa.Column(
+            'phone',
+            sa.String(length=50),
+            nullable=True,
+            comment='Customer contact phone (captured on the new-issue form)',
+        ),
+    )
+
+
+def downgrade() -> None:
+    """Drop tickets.phone."""
+    op.drop_column('tickets', 'phone')