feat(social): follows, favorites, comments, reactions, collections, public profiles

Follow/unfollow users. Recipe favorites. Threaded comments with emoji reactions.
Collections (public/private) with shared member invite. Activity feed.
Public profile pages at /u/[username].

apps/web/app/api/v1/users/me/model-prefs/route.ts

@@ -0,0 +1,42 @@
+import { type NextRequest, NextResponse } from "next/server";
+import { z } from "zod";
+import { requireSession } from "@/lib/api-auth";
+import { db, userModelPrefs, eq } from "@epicure/db";
+
+const Schema = z.object({
+  textProvider: z.string().nullable().optional(),
+  textModel: z.string().nullable().optional(),
+  visionProvider: z.string().nullable().optional(),
+  visionModel: z.string().nullable().optional(),
+  mealPlanProvider: z.string().nullable().optional(),
+  mealPlanModel: z.string().nullable().optional(),
+});
+
+export async function GET() {
+  const { session, response } = await requireSession();
+  if (response) return response;
+
+  const prefs = await db.query.userModelPrefs.findFirst({
+    where: eq(userModelPrefs.userId, session!.user.id),
+  });
+
+  return NextResponse.json(prefs ?? null);
+}
+
+export async function PUT(req: NextRequest) {
+  const { session, response } = await requireSession();
+  if (response) return response;
+
+  const body = Schema.safeParse(await req.json());
+  if (!body.success) return NextResponse.json({ error: "Invalid request" }, { status: 400 });
+
+  await db
+    .insert(userModelPrefs)
+    .values({ id: crypto.randomUUID(), userId: session!.user.id, ...body.data, updatedAt: new Date() })
+    .onConflictDoUpdate({
+      target: userModelPrefs.userId,
+      set: { ...body.data, updatedAt: new Date() },
+    });
+
+  return NextResponse.json({ ok: true });
+}