rename: "Team" billing tier to "Family"

All literal "team" tier-value references renamed to "family" across
API routes, admin UI, OpenAPI schemas, and lib/tiers.ts. The DB enum
value itself is renamed in place via ALTER TYPE ... RENAME VALUE
(migration 0044) rather than drizzle-kit's auto-generated
drop-and-recreate-the-enum migration, which would have failed against
any existing row still holding 'team' — RENAME VALUE preserves
existing data with no cast/backfill needed.

Also adds STRIPE_PLAN.md — a full Stripe billing integration plan
(Checkout+Portal, tier→Price mapping, admin billing dashboard, and a
multi-user Family-group design since Family is meant to cover several
accounts under one subscription, not one payer). Planning only, no
Stripe code yet.

v0.47.0

apps/web/app/admin/storage/page.tsx

@@ -41,7 +41,7 @@ export default async function AdminStoragePage() {
 
   const freePhotos = Number(photosByTier.find((r) => r.tier === "free")?.photoCount ?? 0);
   const proPhotos = Number(photosByTier.find((r) => r.tier === "pro")?.photoCount ?? 0);
-  const teamPhotos = Number(photosByTier.find((r) => r.tier === "team")?.photoCount ?? 0);
+  const familyPhotos = Number(photosByTier.find((r) => r.tier === "family")?.photoCount ?? 0);
 
   return (
     <div className="space-y-6">
@@ -86,11 +86,11 @@ export default async function AdminStoragePage() {
 
         <Card>
           <CardHeader className="flex flex-row items-center justify-between pb-2">
-            <CardTitle className="text-sm font-medium text-muted-foreground">Team Tier Photos</CardTitle>
+            <CardTitle className="text-sm font-medium text-muted-foreground">Family Tier Photos</CardTitle>
             <HardDrive className="h-4 w-4 text-muted-foreground" />
           </CardHeader>
           <CardContent>
-            <div className="text-2xl font-bold">{teamPhotos.toLocaleString()}</div>
+            <div className="text-2xl font-bold">{familyPhotos.toLocaleString()}</div>
           </CardContent>
         </Card>
       </div>