feat: billing/invoice details (full name, address, phone) under Settings > Billing (v0.76.0)

Adds a new user_billing_details table (1:1 with users, separate from the display name) with a form and GET/PUT API route. Full name is required by the form/API; address and phone stay optional. Not wired into Stripe invoicing yet — just captured for future use.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/app/api/v1/users/me/billing-details/route.ts

@@ -0,0 +1,48 @@
+import { NextRequest, NextResponse } from "next/server";
+import { db, userBillingDetails, eq } from "@epicure/db";
+import { requireSession } from "@/lib/api-auth";
+import { z } from "zod";
+
+const PutSchema = z.object({
+  fullName: z.string().trim().min(1).max(200),
+  addressLine1: z.string().trim().max(200).optional(),
+  addressLine2: z.string().trim().max(200).optional(),
+  city: z.string().trim().max(120).optional(),
+  postalCode: z.string().trim().max(20).optional(),
+  country: z.string().trim().max(120).optional(),
+  phone: z.string().trim().max(40).optional(),
+});
+
+export async function GET() {
+  const { session, response } = await requireSession();
+  if (response) return response;
+
+  const details = await db.query.userBillingDetails.findFirst({
+    where: eq(userBillingDetails.userId, session!.user.id),
+  });
+
+  return NextResponse.json({ data: details ?? null });
+}
+
+export async function PUT(req: NextRequest) {
+  const { session, response } = await requireSession();
+  if (response) return response;
+
+  const parsed = PutSchema.safeParse(await req.json());
+  if (!parsed.success) {
+    return NextResponse.json({ error: parsed.error.flatten() }, { status: 400 });
+  }
+
+  const body = parsed.data;
+  const userId = session!.user.id;
+
+  await db
+    .insert(userBillingDetails)
+    .values({ id: crypto.randomUUID(), userId, ...body, updatedAt: new Date() })
+    .onConflictDoUpdate({
+      target: userBillingDetails.userId,
+      set: { ...body, updatedAt: new Date() },
+    });
+
+  return NextResponse.json({ ok: true });
+}