feat(uat-batch-18): interest-berths defaults + a11y loading/hint fixes

- `addInterestBerth` insert-time defaults now match the locked
  multi-berth EOI UX (queue B2):
    is_in_eoi_bundle: true   (was false)
    is_specific_interest: matches `isPrimary` (was always true)
  This means a newly-linked berth is covered by the EOI signature by
  default but the public map only shows the primary as "Under Offer"
  until the rep marks others isSpecificInterest. The two existing
  integration tests pass explicit values so they're unaffected.
- A11y: `set-password` form's password-requirements hint linked via
  aria-describedby so SR users hear the rules on focus.
- A11y: Loading fallbacks on set-password / portal/activate /
  supplemental-info wrapped in role="status" aria-live="polite" with
  sr-only "Loading" copy where only a spinner was visible.

tsc clean. 1419/1419 vitest pass.

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

src/app/(auth)/set-password/page.tsx

@@ -104,7 +104,9 @@ function SetPasswordInner() {
   if (token === null) {
     return (
       <BrandedAuthShell>
-        <div className="text-center text-sm text-gray-500">Loading…</div>
+        <div role="status" aria-live="polite" className="text-center text-sm text-gray-500">
+          Loading…
+        </div>
       </BrandedAuthShell>
     );
   }
@@ -141,10 +143,13 @@ function SetPasswordInner() {
             type="password"
             autoComplete="new-password"
             disabled={isLoading}
+            aria-describedby="password-hint"
             className={cn(errors.password && 'border-destructive focus-visible:ring-destructive')}
             {...register('password')}
           />
-          <p className="text-xs text-gray-500">At least {MIN_LENGTH} characters.</p>
+          <p id="password-hint" className="text-xs text-gray-500">
+            At least {MIN_LENGTH} characters.
+          </p>
           {errors.password && <p className="text-sm text-destructive">{errors.password.message}</p>}
         </div>
 

src/app/(portal)/portal/activate/page.tsx

@@ -6,7 +6,11 @@ export default function PortalActivatePage() {
   return (
     <Suspense
       fallback={
-        <div className="min-h-screen flex items-center justify-center bg-gray-50 text-sm text-gray-500">
+        <div
+          role="status"
+          aria-live="polite"
+          className="min-h-screen flex items-center justify-center bg-gray-50 text-sm text-gray-500"
+        >
           Loading…
         </div>
       }

src/app/public/supplemental-info/[token]/page.tsx

@@ -140,8 +140,9 @@ export default function SupplementalInfoPage({ params }: PageProps) {
   if (loading) {
     return (
       <BrandedAuthShell>
-        <div className="flex items-center justify-center py-8">
+        <div role="status" aria-live="polite" className="flex items-center justify-center py-8">
           <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
+          <span className="sr-only">Loading</span>
         </div>
       </BrandedAuthShell>
     );