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]/block/route.ts

@@ -0,0 +1,44 @@
+import { NextRequest, NextResponse } from "next/server";
+import { db, users, userBlocks, userFollows, eq, and, or } from "@epicure/db";
+import { requireSession } from "@/lib/api-auth";
+
+type Params = { params: Promise<{ username: string }> };
+
+export async function POST(_req: NextRequest, { params }: Params) {
+  const { session, response } = await requireSession();
+  if (response) return response;
+  const { username } = await params;
+
+  const target = await db.query.users.findFirst({ where: eq(users.username, username) });
+  if (!target) return NextResponse.json({ error: "Not found" }, { status: 404 });
+  if (target.id === session!.user.id) return NextResponse.json({ error: "Cannot block yourself" }, { status: 400 });
+
+  await db.insert(userBlocks)
+    .values({ blockerId: session!.user.id, blockedId: target.id })
+    .onConflictDoNothing();
+
+  // Blocking severs any existing follow relationship in either direction.
+  await db.delete(userFollows).where(
+    or(
+      and(eq(userFollows.followerId, session!.user.id), eq(userFollows.followingId, target.id)),
+      and(eq(userFollows.followerId, target.id), eq(userFollows.followingId, session!.user.id))
+    )
+  );
+
+  return NextResponse.json({ blocked: true });
+}
+
+export async function DELETE(_req: NextRequest, { params }: Params) {
+  const { session, response } = await requireSession();
+  if (response) return response;
+  const { username } = await params;
+
+  const target = await db.query.users.findFirst({ where: eq(users.username, username) });
+  if (!target) return NextResponse.json({ error: "Not found" }, { status: 404 });
+
+  await db.delete(userBlocks).where(
+    and(eq(userBlocks.blockerId, session!.user.id), eq(userBlocks.blockedId, target.id))
+  );
+
+  return NextResponse.json({ blocked: false });
+}