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/migrations/0001_init.sql

@@ -1,42 +1,49 @@
--- Schema iniziale licenze MusicTools
+-- Schema MariaDB iniziale per MusicTools licenze.
+-- Tutto utf8mb4 + InnoDB con FK abilitate.
+
+SET NAMES utf8mb4;
 
 CREATE TABLE IF NOT EXISTS licenses (
-  id           INTEGER PRIMARY KEY AUTOINCREMENT,
-  license_key  TEXT NOT NULL UNIQUE,
-  email        TEXT NOT NULL,
-  status       TEXT NOT NULL DEFAULT 'active',  -- active | revoked | refunded
-  source       TEXT,                            -- es. 'lemonsqueezy', 'manual'
-  order_id     TEXT,                            -- id dell'ordine LS
-  created_at   INTEGER NOT NULL,
-  updated_at   INTEGER NOT NULL
-);
-
-CREATE INDEX IF NOT EXISTS idx_licenses_email ON licenses(email);
+  id            INT UNSIGNED NOT NULL AUTO_INCREMENT,
+  license_key   VARCHAR(64) NOT NULL,
+  email         VARCHAR(255) NOT NULL,
+  status        ENUM('active','revoked','refunded') NOT NULL DEFAULT 'active',
+  source        VARCHAR(32) NULL,
+  order_id      VARCHAR(64) NULL,
+  created_at    BIGINT UNSIGNED NOT NULL,
+  updated_at    BIGINT UNSIGNED NOT NULL,
+  PRIMARY KEY (id),
+  UNIQUE KEY uq_licenses_key (license_key),
+  KEY idx_licenses_email (email),
+  KEY idx_licenses_order_id (order_id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
 CREATE TABLE IF NOT EXISTS activations (
-  id           INTEGER PRIMARY KEY AUTOINCREMENT,
-  license_id   INTEGER NOT NULL REFERENCES licenses(id) ON DELETE CASCADE,
-  device_id    TEXT NOT NULL,
-  device_name  TEXT,
-  app_version  TEXT,
-  activated_at INTEGER NOT NULL,
-  last_seen_at INTEGER NOT NULL,
-  revoked_at   INTEGER,
-  UNIQUE (license_id, device_id)
-);
-
-CREATE INDEX IF NOT EXISTS idx_activations_license ON activations(license_id);
+  id            INT UNSIGNED NOT NULL AUTO_INCREMENT,
+  license_id    INT UNSIGNED NOT NULL,
+  device_id     VARCHAR(64) NOT NULL,
+  device_name   VARCHAR(255) NULL,
+  app_version   VARCHAR(32) NULL,
+  activated_at  BIGINT UNSIGNED NOT NULL,
+  last_seen_at  BIGINT UNSIGNED NOT NULL,
+  revoked_at    BIGINT UNSIGNED NULL,
+  PRIMARY KEY (id),
+  UNIQUE KEY uq_activations_lic_dev (license_id, device_id),
+  KEY idx_activations_license (license_id),
+  CONSTRAINT fk_activations_license
+    FOREIGN KEY (license_id) REFERENCES licenses(id) ON DELETE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
 CREATE TABLE IF NOT EXISTS releases (
-  id           INTEGER PRIMARY KEY AUTOINCREMENT,
-  version      TEXT NOT NULL,
-  platform     TEXT NOT NULL,            -- macos | windows
-  r2_key       TEXT NOT NULL,            -- chiave dentro il bucket R2
-  size_bytes   INTEGER,
-  sha256       TEXT,
-  notes        TEXT,
-  published_at INTEGER NOT NULL,
-  UNIQUE (version, platform)
-);
-
-CREATE INDEX IF NOT EXISTS idx_releases_platform_pub ON releases(platform, published_at DESC);
+  id            INT UNSIGNED NOT NULL AUTO_INCREMENT,
+  version       VARCHAR(32) NOT NULL,
+  platform      ENUM('macos','windows') NOT NULL,
+  file_path     VARCHAR(512) NOT NULL,
+  size_bytes    BIGINT UNSIGNED NULL,
+  sha256        CHAR(64) NULL,
+  notes         TEXT NULL,
+  published_at  BIGINT UNSIGNED NOT NULL,
+  PRIMARY KEY (id),
+  UNIQUE KEY uq_releases_ver_plat (version, platform),
+  KEY idx_releases_platform_pub (platform, published_at DESC)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;