fix(audit-wave-11): mobile dvh + multi-port slug-first apiFetch

**mobile-pwa-auditor H4 — mobile shell uses min-h-screen**

`min-h-screen` resolves to `100vh` on iOS Safari, which is the LARGE
viewport height (URL bar collapsed). On first paint the page renders
~75–100px taller than visible, and reps see a blank strip past the
bottom tab bar until the URL bar collapses on first scroll. Swap
`min-h-screen` → `min-h-[100dvh]` in `mobile-layout.tsx`. The scanner
layout already does this correctly.

**multi-port-auditor C1 — port-switcher race / cross-port bleed**

`apiFetch` previously preferred Zustand for the X-Port-Id header and
only consulted the URL slug as a fallback. Zustand lags by one render
behind `PortProvider`'s reconcile effect; clicking from /port-A to
/port-B fired the first round of queries with X-Port-Id = port-A
while the page chrome rendered port-B → silent cross-port data bleed
in the UI.

Make the URL slug authoritative: read it first via
`window.location.pathname` + `resolvePortIdFromSlug`, fall back to
Zustand only on global routes (/dashboard) without a port slug.

**multi-port-auditor C3 — defaultPortId silently stripped**

`withAuth` reads `preferences.defaultPortId` as the X-Port-Id
fallback, but `/me` PATCH's `.strict()` schema + ALLOWED_PREF_KEYS
allow-list silently dropped the key on every write. The fallback was
therefore dead — super-admins always landed alphabetically-first.

Add `defaultPortId: z.string().uuid().optional()` to the strict
schema and include it in ALLOWED_PREF_KEYS so super-admins can
persist their last-picked port.

Tests 1315/1315.

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

src/components/layout/mobile/mobile-layout.tsx

@@ -21,12 +21,12 @@ export function MobileLayout({ children }: { children: ReactNode }) {
   const [searchOpen, setSearchOpen] = useState(false);
 
   return (
-    <div data-shell="mobile" className="min-h-screen bg-background">
+    <div data-shell="mobile" className="min-h-[100dvh] bg-background">
       <MobileLayoutProvider>
         <MobileTopbar />
         <main
           className={cn(
-            'px-4 min-h-screen',
+            'px-4 min-h-[100dvh]',
             // 56px topbar + safe-area + 16px breathing room
             'pt-[calc(56px+env(safe-area-inset-top)+1rem)]',
             // 56px tab bar + safe-area + 32px breathing room