feat(02-02): add admin client list page and create-client flow

- /admin page: Server Component fetching all clients with payment badges
- ClientRow component with Acconto/Saldo status badges and secret link
- /admin/clients/new: form wired to createClient Server Action
- createClient action: Zod validation, inserts client + 2 payment stubs (Acconto 50%, Saldo 50%)
- Token auto-generated server-side via nanoid $defaultFn
- Redirects to /admin/clients/[id] after creation; revalidates /admin

src/app/admin/clients/new/actions.ts

@@ -0,0 +1,59 @@
+"use server";
+
+import { redirect } from "next/navigation";
+import { revalidatePath } from "next/cache";
+import { z } from "zod";
+import { db } from "@/db";
+import { clients, payments } from "@/db/schema";
+
+const createClientSchema = z.object({
+  name: z.string().min(1, "Nome richiesto"),
+  brand_name: z.string().min(1, "Nome brand richiesto"),
+  brief: z.string().min(1, "Brief richiesto"),
+});
+
+export async function createClient(formData: FormData) {
+  const raw = {
+    name: formData.get("name") as string,
+    brand_name: formData.get("brand_name") as string,
+    brief: formData.get("brief") as string,
+  };
+
+  const parsed = createClientSchema.safeParse(raw);
+  if (!parsed.success) {
+    // In v1 return errors as thrown string — form displays validation inline
+    throw new Error(
+      parsed.error.issues.map((i) => i.message).join(", ")
+    );
+  }
+
+  // Insert client — token and id are auto-generated by $defaultFn(() => nanoid())
+  const [newClient] = await db
+    .insert(clients)
+    .values({
+      name: parsed.data.name,
+      brand_name: parsed.data.brand_name,
+      brief: parsed.data.brief,
+    })
+    .returning({ id: clients.id, token: clients.token });
+
+  // Always create two payment stubs per client — Acconto 50% and Saldo 50%
+  // Amounts default to 0 until admin sets accepted_total; admin updates separately
+  await db.insert(payments).values([
+    {
+      client_id: newClient.id,
+      label: "Acconto 50%",
+      amount: "0",
+      status: "da_saldare",
+    },
+    {
+      client_id: newClient.id,
+      label: "Saldo 50%",
+      amount: "0",
+      status: "da_saldare",
+    },
+  ]);
+
+  revalidatePath("/admin");
+  redirect(`/admin/clients/${newClient.id}`);
+}