flatten app to repo root and update docker deployment for single-stack runtime

app/api/watchlist/[id]/route.ts

@@ -0,0 +1,29 @@
+import { jsonError } from '@/lib/server/http';
+import { withStore } from '@/lib/server/store';
+
+type Context = {
+  params: Promise<{ id: string }>;
+};
+
+export async function DELETE(_request: Request, context: Context) {
+  const { id } = await context.params;
+  const numericId = Number(id);
+
+  if (!Number.isInteger(numericId) || numericId <= 0) {
+    return jsonError('Invalid watchlist id', 400);
+  }
+
+  let removed = false;
+
+  await withStore((store) => {
+    const next = store.watchlist.filter((item) => item.id !== numericId);
+    removed = next.length !== store.watchlist.length;
+    store.watchlist = next;
+  });
+
+  if (!removed) {
+    return jsonError('Watchlist item not found', 404);
+  }
+
+  return Response.json({ success: true });
+}