fix(layout): mobile UX cleanup + interest-stage legend popover

Mobile UX:
- Hide ColumnPicker on `< sm` viewports (cards, no columns to toggle).
- Hide kanban toggle in interest list on mobile and snap viewMode back
  to 'table' if the persisted choice was 'board'.
- Drop dead "Inbox" link from the More-sheet (email/IMAP feature is
  deferred per sidebar.tsx note).
- Repoint Notifications nav from `/notifications` (no page.tsx — 404)
  to `/notifications/preferences` and re-label as "Notification
  preferences" (the bell stays the surface for actual notifications).
- Hide Website Analytics on both desktop sidebar and mobile More-sheet
  when Umami isn't configured for the port (`useUmamiActive()`).

Interests:
- New `<StageLegend>` popover button in the filter row decodes the
  card stripe colours to pipeline stage names, kept in sync with
  `STAGE_DOT` automatically.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/layout/sidebar.tsx

@@ -34,6 +34,7 @@ import { Separator } from '@/components/ui/separator';
 import { ScrollArea } from '@/components/ui/scroll-area';
 import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from '@/components/ui/tooltip';
 import { UserMenu } from '@/components/layout/user-menu';
+import { useUmamiActive } from '@/components/website-analytics/use-website-analytics';
 import type { UserPortRole } from '@/lib/db/schema/users';
 import type { Role } from '@/lib/db/schema/users';
 import type { Port } from '@/lib/db/schema/ports';
@@ -76,6 +77,8 @@ interface NavSection {
   marinaRequired?: boolean;
   /** When true, only render if the user has residential-side access. */
   residentialRequired?: boolean;
+  /** When true, only render if Umami analytics is wired up for the port. */
+  umamiRequired?: boolean;
 }
 
 function buildNavSections(portSlug: string | undefined): NavSection[] {
@@ -140,10 +143,12 @@ function buildNavSections(portSlug: string | undefined): NavSection[] {
     {
       title: 'Insights',
       marinaRequired: true,
+      umamiRequired: true,
       items: [
         // Marketing / Umami integration. Distinct from the main dashboard
         // (which is sales-focused) so the audience and the metrics don't
-        // compete for visual real estate.
+        // compete for visual real estate. Whole section is hidden when
+        // Umami isn't wired up — see SidebarContent.
         {
           href: `${base}/website-analytics`,
           label: 'Website analytics',
@@ -250,6 +255,8 @@ function SidebarContent({
   const pathname = usePathname();
   const [adminExpanded, setAdminExpanded] = useState(true);
   const sections = buildNavSections(portSlug);
+  const umami = useUmamiActive('today');
+  const umamiConfigured = umami.data?.error !== 'umami_not_configured';
 
   // Small label under the user identity when the user has access to more
   // than one port — disambiguates which port is currently active without
@@ -324,6 +331,7 @@ function SidebarContent({
               if (section.adminRequired && !hasAdminAccess) return null;
               if (section.marinaRequired && !hasMarinaAccess) return null;
               if (section.residentialRequired && !hasResidentialAccess) return null;
+              if (section.umamiRequired && !umamiConfigured) return null;
 
               return (
                 <div key={section.title}>