feat: add client disable/deletion with soft-delete (#67)

Add soft-delete support for clients: disable is the default action
(hiding from client list and booking flow), with permanent deletion
requiring explicit type-to-confirm. Disabled clients remain in
reporting and can be re-enabled by staff.

- Add client_status enum (active/disabled) and disabled_at column
- API defaults GET /api/clients to active-only, ?includeDisabled=true shows all
- PATCH /api/clients/:id accepts status field for disable/enable
- DELETE requires ?confirm=true query param
- Booking flow skips disabled clients
- Frontend: show disabled toggle, disable/enable buttons, delete confirmation modal

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/e2e/tests/clients.spec.ts

@@ -14,6 +14,9 @@ const MOCK_CLIENTS = [
     phone: "555-0101",
     address: null,
     notes: null,
+    emailOptOut: false,
+    status: "active",
+    disabledAt: null,
     createdAt: "2026-01-01T00:00:00.000Z",
     updatedAt: "2026-01-01T00:00:00.000Z",
   },
@@ -24,6 +27,9 @@ const MOCK_CLIENTS = [
     phone: null,
     address: null,
     notes: null,
+    emailOptOut: false,
+    status: "active",
+    disabledAt: null,
     createdAt: "2026-01-02T00:00:00.000Z",
     updatedAt: "2026-01-02T00:00:00.000Z",
   },