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/components/layout/sidebar.tsx

@@ -61,6 +61,11 @@ interface SidebarProps {
    *  the dashboard layout. Defaults to true (feature on) per port when
    *  the map is missing for the active port. */
   expensesModuleByPort?: Record<string, boolean>;
+  /** Per-port `residential_module_enabled` resolution. Gates the entire
+   *  "Residential" sidebar section. Resolved server-side in the dashboard
+   *  layout. Defaults to true (feature on) per port when the map is
+   *  missing for the active port. */
+  residentialModuleByPort?: Record<string, boolean>;
 }
 
 interface NavItem {
@@ -78,6 +83,9 @@ interface NavSection {
   marinaRequired?: boolean;
   /** When true, only render if the user has residential-side access. */
   residentialRequired?: boolean;
+  /** When true, only render if the residential module is enabled for the
+   *  current port. Resolved against `residentialModuleByPort`. */
+  requiresResidentialModule?: boolean;
   /** When true, only render if Umami analytics is wired up for the port. */
   umamiRequired?: boolean;
 }
@@ -119,6 +127,7 @@ function buildNavSections(portSlug: string | undefined): NavSection[] {
     {
       title: 'Residential',
       residentialRequired: true,
+      requiresResidentialModule: true,
       items: [
         {
           href: `${base}/residential/clients`,
@@ -280,6 +289,7 @@ function SidebarContent({
   hasResidentialAccess,
   tenanciesModuleEnabled,
   expensesModuleEnabled,
+  residentialModuleEnabled,
   user,
   ports,
   currentPort,
@@ -295,6 +305,7 @@ function SidebarContent({
   hasResidentialAccess: boolean;
   tenanciesModuleEnabled: boolean;
   expensesModuleEnabled: boolean;
+  residentialModuleEnabled: boolean;
   user?: SidebarProps['user'];
   ports?: Port[];
   currentPort: Port | null;
@@ -388,6 +399,7 @@ function SidebarContent({
               if (section.adminRequired && !hasAdminAccess) return null;
               if (section.marinaRequired && !hasMarinaAccess) return null;
               if (section.residentialRequired && !hasResidentialAccess) return null;
+              if (section.requiresResidentialModule && !residentialModuleEnabled) return null;
               if (section.umamiRequired && !umamiConfigured) return null;
 
               return (
@@ -514,6 +526,7 @@ export function Sidebar({
   portLogoUrls,
   tenanciesModuleByPort,
   expensesModuleByPort,
+  residentialModuleByPort,
 }: SidebarProps) {
   // Sidebar collapse removed - design preference is the always-expanded
   // form. Forcibly false; the store flag stays for backwards-compat with
@@ -532,6 +545,12 @@ export function Sidebar({
   const expensesModuleEnabled = currentPortId
     ? (expensesModuleByPort?.[currentPortId] ?? true)
     : true;
+  // Residential defaults to enabled when the port's entry is missing -
+  // the registry default is `true`, so a port that's never explicitly
+  // toggled the feature keeps the section visible.
+  const residentialModuleEnabled = currentPortId
+    ? (residentialModuleByPort?.[currentPortId] ?? true)
+    : true;
 
   // Super admins see every section regardless of role rows.
   const hasAdminAccess =
@@ -565,6 +584,7 @@ export function Sidebar({
         hasResidentialAccess={hasResidentialAccess}
         tenanciesModuleEnabled={tenanciesModuleEnabled}
         expensesModuleEnabled={expensesModuleEnabled}
+        residentialModuleEnabled={residentialModuleEnabled}
         user={user}
         ports={ports}
         currentPort={currentPort}