feat(residential-toggle): port-level module gate for Residential

Adds a `residential_module_enabled` port setting (default ON) that
hides/disables the entire Residential surface when an admin turns it
off, mirroring the Tenancies / Invoices / Expenses module-toggle
pattern. Disabling is a soft hide — residential clients/interests are
preserved and reappear on re-enable.

Surfaces gated:
- Route guard: new residential/layout.tsx renders ModuleDisabledPage
  (covers all 5 residential pages)
- Sidebar "Residential" section + mobile more-sheet tile (SSR-resolved
  residentialModuleByPort threaded layout → app-shell → sidebar)
- Global search: residential client/interest buckets early-return at
  the shared chokepoint so disabled-port records don't dead-end
- Public intake: /api/public/residential-inquiries 404s when off
- Admin Switch in settings-manager (writes via settings PUT)

Service TDD'd (residential-module.test.ts, 6 tests) plus a
disabled-port rejection test on the public endpoint. tsc + lint clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/(dashboard)/[portSlug]/residential/layout.tsx

@@ -0,0 +1,44 @@
+import { eq } from 'drizzle-orm';
+
+import { db } from '@/lib/db';
+import { ports as portsTable } from '@/lib/db/schema/ports';
+import { isResidentialModuleEnabled } from '@/lib/services/residential-module.service';
+import { ModuleDisabledPage } from '@/components/shared/module-disabled-page';
+
+interface ResidentialLayoutProps {
+  children: React.ReactNode;
+  params: Promise<{ portSlug: string }>;
+}
+
+/**
+ * Layout-level gate for the entire /residential subtree (clients +
+ * interests, list + detail). When the port has
+ * residential_module_enabled = false, every route under /residential
+ * renders the ModuleDisabledPage instead of the real content. This is
+ * the route-level half of the "hybrid hide+block" model (the sidebar
+ * "Residential" section + mobile entry are independently hidden via
+ * residentialModuleByPort on the SSR-resolved sidebar prop).
+ *
+ * Using a layout rather than per-page guards means: (a) one place to
+ * change the gate logic, (b) nested routes ([id]) are covered
+ * automatically, (c) the children subtree never mounts when disabled,
+ * so its data-fetching effects don't fire.
+ */
+export default async function ResidentialLayout({ children, params }: ResidentialLayoutProps) {
+  const { portSlug } = await params;
+  const port = await db.query.ports.findFirst({
+    where: eq(portsTable.slug, portSlug),
+    columns: { id: true },
+  });
+  if (!port) return children;
+  const enabled = await isResidentialModuleEnabled(port.id);
+  if (enabled) return children;
+  return (
+    <ModuleDisabledPage
+      moduleName="Residential"
+      description="The Residential clients and interests pipeline is turned off for this port. Existing residential records are preserved and will reappear when the module is re-enabled."
+      settingsHref={`/${portSlug}/admin/settings`}
+      fallbackHref={`/${portSlug}/dashboard`}
+    />
+  );
+}