feat: user blocking and content reporting/flagging

- user_blocks table (composite PK), Block/Unblock button on profiles.
  Blocking severs any existing follow relationship both ways and
  prevents the blocked party from following, commenting on the
  blocker's recipes, or the blocker from seeing their comments.
- reports table (recipe/comment/user targets, pending/reviewed/
  dismissed status). ReportButton on comments, admin review queue at
  /admin/reports with dismiss/mark-reviewed actions, audit-logged.

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

apps/web/app/api/v1/users/[username]/follow/route.ts

@@ -3,6 +3,7 @@ import { db, users, userFollows, eq, and } from "@epicure/db";
 import { requireSession } from "@/lib/api-auth";
 import { applyRateLimit } from "@/lib/rate-limit";
 import { createNotification } from "@/lib/notifications";
+import { isBlockedEitherWay } from "@/lib/blocks";
 
 type Params = { params: Promise<{ username: string }> };
 
@@ -19,6 +20,10 @@ export async function POST(_req: NextRequest, { params }: Params) {
   if (!target) return NextResponse.json({ error: "Not found" }, { status: 404 });
   if (target.id === session!.user.id) return NextResponse.json({ error: "Cannot follow yourself" }, { status: 400 });
 
+  if (await isBlockedEitherWay(session!.user.id, target.id)) {
+    return NextResponse.json({ error: "Not found" }, { status: 404 });
+  }
+
   await db.insert(userFollows)
     .values({ followerId: session!.user.id, followingId: target.id })
     .onConflictDoNothing();