feat: client edit/delete/archive + time tracker + analytics time section

Schema:
- clients.archived boolean (default false)
- time_entries table (client_id, started_at, ended_at, duration_seconds)

Client management:
- /admin/clients/[id]/edit — form pre-compilato con nome, brand, brief
- ClientActions: Modifica / Archivia / Elimina con doppia conferma
- setClientArchived: toggle archiviazione senza perdere dati
- deleteClient: elimina con cascade, redirect a /admin
- Admin list: toggle "Mostra archiviati" via ?archived=1, righe archiviate opache

Time tracker:
- startTimer: crea sessione, ferma automaticamente quella precedente
- stopTimer: chiude sessione, calcola duration_seconds
- TimerCell: ▶/⏹ per ogni cliente, contatore live in secondi, totale cumulativo
- Una sola sessione attiva alla volta su tutta la lista

Analytics:
- Sezione "Fatturato" (invariata) + sezione "Tempo tracciato" separata
- Ore totali per anno + barre orizzontali per cliente
- getTotalTrackedHours, getTimeByClient queries

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

src/lib/analytics-queries.ts

@@ -1,5 +1,5 @@
 import { db } from "@/db";
-import { clients, payments } from "@/db/schema";
+import { clients, payments, time_entries } from "@/db/schema";
 import { sql, and, eq } from "drizzle-orm";
 
 export async function getAnalyticsByYear(year: number) {
@@ -68,4 +68,50 @@ export async function getAvailableYears(): Promise<number[]> {
   const currentYear = new Date().getFullYear();
   if (!years.includes(currentYear)) years.push(currentYear);
   return years.sort((a, b) => b - a);
+}
+
+// ── Time tracking ─────────────────────────────────────────────────────────────
+
+export type ClientTimeRow = {
+  clientId: string;
+  clientName: string;
+  totalSeconds: number;
+};
+
+export async function getTimeByClient(year: number): Promise<ClientTimeRow[]> {
+  const rows = await db
+    .select({
+      client_id: time_entries.client_id,
+      total: sql<string>`coalesce(sum(${time_entries.duration_seconds}), 0)`,
+    })
+    .from(time_entries)
+    .where(
+      sql`${time_entries.ended_at} is not null
+          and extract(year from ${time_entries.started_at}) = ${year}`
+    )
+    .groupBy(time_entries.client_id);
+
+  if (rows.length === 0) return [];
+
+  const allClients = await db.select({ id: clients.id, name: clients.name }).from(clients);
+  const nameMap = new Map(allClients.map((c) => [c.id, c.name]));
+
+  return rows
+    .map((r) => ({
+      clientId: r.client_id,
+      clientName: nameMap.get(r.client_id) ?? r.client_id,
+      totalSeconds: parseInt(r.total),
+    }))
+    .sort((a, b) => b.totalSeconds - a.totalSeconds);
+}
+
+export async function getTotalTrackedHours(year: number): Promise<number> {
+  const [row] = await db
+    .select({ total: sql<string>`coalesce(sum(${time_entries.duration_seconds}), 0)` })
+    .from(time_entries)
+    .where(
+      sql`${time_entries.ended_at} is not null
+          and extract(year from ${time_entries.started_at}) = ${year}`
+    );
+  return Math.round(parseInt(row?.total ?? "0") / 3600 * 10) / 10;
 }