feat: add analytics query helpers for admin financial reporting

Provides getAnalyticsByYear, getMonthlyCollected, and getAvailableYears
to power the admin dashboard analytics view (not yet wired to a page).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/analytics-queries.ts

@@ -0,0 +1,71 @@
+import { db } from "@/db";
+import { clients, payments } from "@/db/schema";
+import { sql, and, eq } from "drizzle-orm";
+
+export async function getAnalyticsByYear(year: number) {
+  const [contracted] = await db
+    .select({ total: sql<string>`coalesce(sum(${clients.accepted_total}::numeric), 0)` })
+    .from(clients)
+    .where(sql`extract(year from ${clients.created_at}) = ${year}`);
+
+  const [clientsRow] = await db
+    .select({ count: sql<string>`count(*)` })
+    .from(clients)
+    .where(sql`extract(year from ${clients.created_at}) = ${year}`);
+
+  const [collected] = await db
+    .select({ total: sql<string>`coalesce(sum(${payments.amount}::numeric), 0)` })
+    .from(payments)
+    .where(
+      and(
+        eq(payments.status, "saldato"),
+        sql`${payments.paid_at} is not null and extract(year from ${payments.paid_at}) = ${year}`
+      )
+    );
+
+  const [pending] = await db
+    .select({ total: sql<string>`coalesce(sum(${payments.amount}::numeric), 0)` })
+    .from(payments)
+    .where(sql`${payments.status} in ('da_saldare', 'inviata')`);
+
+  return {
+    contracted: parseFloat(contracted?.total ?? "0"),
+    collected: parseFloat(collected?.total ?? "0"),
+    clientsAcquired: parseInt(clientsRow?.count ?? "0"),
+    pending: parseFloat(pending?.total ?? "0"),
+  };
+}
+
+export async function getMonthlyCollected(year: number): Promise<number[]> {
+  const rows = await db
+    .select({
+      month: sql<number>`extract(month from ${payments.paid_at})::int`,
+      total: sql<string>`coalesce(sum(${payments.amount}::numeric), 0)`,
+    })
+    .from(payments)
+    .where(
+      and(
+        eq(payments.status, "saldato"),
+        sql`${payments.paid_at} is not null and extract(year from ${payments.paid_at}) = ${year}`
+      )
+    )
+    .groupBy(sql`extract(month from ${payments.paid_at})`);
+
+  const byMonth: number[] = Array(12).fill(0);
+  for (const row of rows) {
+    byMonth[(row.month as number) - 1] = parseFloat(row.total);
+  }
+  return byMonth;
+}
+
+export async function getAvailableYears(): Promise<number[]> {
+  const rows = await db
+    .select({ year: sql<number>`extract(year from ${clients.created_at})::int` })
+    .from(clients)
+    .groupBy(sql`extract(year from ${clients.created_at})`);
+
+  const years = rows.map((r) => r.year as number);
+  const currentYear = new Date().getFullYear();
+  if (!years.includes(currentYear)) years.push(currentYear);
+  return years.sort((a, b) => b - a);
+}