Riscrivi backend per hosting Node/MariaDB/PM2 (no Cloudflare)

L'utente ha un hosting Virtualmin esistente (musictools.djluza.com)
con Apache + Node 20 + MariaDB + PM2. Tutta l'infrastruttura
Cloudflare (Workers/D1/R2/Pages) e' rimpiazzata con un backend
Express che gira sul server gia' presente, a costo zero.

Cambia:
- server/src/*.ts (Workers) -> server/src/*.js (Node ESM puro)
- D1 (sqlite) -> MariaDB 10.11 via mysql2/promise
- R2 (storage) -> filesystem locale ~/builds/ + signed URL HMAC
- wrangler.toml -> ecosystem.config.cjs (PM2)
- Aggiunto src/migrate.js: runner SQL idempotente

Endpoints invariati - l'app desktop non vede differenze:
- POST /api/license/{activate,validate,deactivate}
- GET  /api/latest, /api/download
- POST /api/webhook/lemonsqueezy
- GET  /api/health

README riscritto con istruzioni complete: creazione DB,
deploy via rsync/git, config Apache reverse proxy via
Virtualmin, gestione PM2, backup, workflow release.

Email rimane su Resend (deliverability) - free tier sufficiente.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

server/src/license.js

@@ -0,0 +1,136 @@
+import crypto from "node:crypto";
+import { one, exec } from "./db.js";
+import { signJwt, verifyJwt } from "./jwt.js";
+
+const MAX_ACTIVATIONS = Number(process.env.MAX_ACTIVATIONS || 3);
+const TOKEN_TTL_DAYS = Number(process.env.TOKEN_TTL_DAYS || 30);
+
+const now = () => Math.floor(Date.now() / 1000);
+const normEmail = (s) => String(s || "").trim().toLowerCase();
+const normKey = (s) => String(s || "").trim().toUpperCase();
+
+async function issueToken(license, deviceId) {
+  const t = now();
+  return signJwt({
+    sub: String(license.id),
+    key_id: license.license_key,
+    email: license.email,
+    device_id: deviceId,
+    iat: t,
+    exp: t + TOKEN_TTL_DAYS * 86400,
+  }, process.env.JWT_SECRET);
+}
+
+export async function activate(req, res) {
+  const { key, email, device_id, device_name, app_version } = req.body || {};
+  const K = normKey(key), E = normEmail(email);
+  const D = String(device_id || "").trim();
+  if (!K || !E || !D) {
+    return res.status(400).json({ error: "Missing key, email or device_id" });
+  }
+
+  const license = await one(
+    "SELECT id, license_key, email, status FROM licenses WHERE license_key=? AND email=? LIMIT 1",
+    [K, E],
+  );
+  if (!license) {
+    return res.status(404).json({ error: "Chiave o email non corrispondono a un acquisto." });
+  }
+  if (license.status !== "active") {
+    return res.status(403).json({ error: "Licenza non piu' valida (rimborsata o revocata)." });
+  }
+
+  const t = now();
+  const existing = await one(
+    "SELECT id FROM activations WHERE license_id=? AND device_id=? LIMIT 1",
+    [license.id, D],
+  );
+
+  if (existing) {
+    await exec(
+      `UPDATE activations SET app_version=?, device_name=?, last_seen_at=?, revoked_at=NULL
+       WHERE id=?`,
+      [app_version || null, device_name || null, t, existing.id],
+    );
+  } else {
+    const row = await one(
+      "SELECT COUNT(*) AS n FROM activations WHERE license_id=? AND revoked_at IS NULL",
+      [license.id],
+    );
+    if ((row?.n || 0) >= MAX_ACTIVATIONS) {
+      return res.status(409).json({
+        error: `Hai gia attivato la licenza su ${MAX_ACTIVATIONS} dispositivi. Disattivane uno per usarla qui.`,
+      });
+    }
+    await exec(
+      `INSERT INTO activations
+        (license_id, device_id, device_name, app_version, activated_at, last_seen_at)
+       VALUES (?, ?, ?, ?, ?, ?)`,
+      [license.id, D, device_name || null, app_version || null, t, t],
+    );
+  }
+
+  const token = await issueToken(license, D);
+  res.json({ token, activated_at: t, email: license.email });
+}
+
+export async function validate(req, res) {
+  const { token, device_id, app_version } = req.body || {};
+  const T = String(token || "").trim();
+  const D = String(device_id || "").trim();
+  if (!T || !D) return res.status(400).json({ error: "Missing token or device_id" });
+
+  const claims = verifyJwt(T, process.env.JWT_SECRET);
+  if (!claims) return res.status(401).json({ error: "Token invalido o scaduto" });
+  if (claims.device_id !== D) return res.status(401).json({ error: "device_id mismatch" });
+
+  const license = await one(
+    "SELECT id, license_key, email, status FROM licenses WHERE id=?",
+    [claims.sub],
+  );
+  if (!license || license.status !== "active") {
+    return res.status(401).json({ error: "Licenza non attiva" });
+  }
+  const act = await one(
+    "SELECT id, revoked_at FROM activations WHERE license_id=? AND device_id=?",
+    [license.id, D],
+  );
+  if (!act || act.revoked_at !== null) {
+    return res.status(401).json({ error: "Attivazione non trovata o revocata" });
+  }
+
+  await exec(
+    "UPDATE activations SET last_seen_at=?, app_version=? WHERE id=?",
+    [now(), app_version || null, act.id],
+  );
+
+  const fresh = await issueToken(license, D);
+  res.json({ token: fresh, email: license.email });
+}
+
+export async function deactivate(req, res) {
+  const { token, device_id } = req.body || {};
+  const T = String(token || "").trim();
+  const D = String(device_id || "").trim();
+  if (!T || !D) return res.status(400).json({ error: "Missing token or device_id" });
+
+  const claims = verifyJwt(T, process.env.JWT_SECRET);
+  if (!claims) return res.status(401).json({ error: "Token invalido" });
+  if (claims.device_id !== D) return res.status(401).json({ error: "device_id mismatch" });
+
+  await exec(
+    `UPDATE activations SET revoked_at=?
+     WHERE license_id=? AND device_id=? AND revoked_at IS NULL`,
+    [now(), claims.sub, D],
+  );
+  res.json({ ok: true });
+}
+
+// Esposto per uso interno (es. webhook genera chiave nuova)
+export function generateLicenseKey() {
+  const alphabet = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789";
+  const buf = crypto.randomBytes(16);
+  const chars = Array.from(buf, (b) => alphabet[b % alphabet.length]);
+  return [chars.slice(0,4), chars.slice(4,8), chars.slice(8,12), chars.slice(12,16)]
+    .map((g) => g.join("")).join("-");
+}