license: force UTC + fixed-Z date format on both sides

Symptom: "Réponse serveur non authentifiée (signature invalide)" on
license activation. Root cause: PHP \DateTimeInterface::ATOM emits the
server's local timezone offset (e.g. +02:00 on a CET host), while the
C# canonicalizer emitted +00:00 after ToUniversalTime(). Same instant,
different string, different bytes, signature mismatch.

Server (ValidateLicense.php):
- All timestamps now built with `new DateTimeZone('UTC')` and formatted
  as 'Y-m-d\TH:i:s\Z' — fixed string, no offset variation.
- Reads issued_at / download_entitlement_until from MySQL as UTC; the
  display is consistent with what the client sees.

Client (LicenseService.cs):
- FormatDateAtom now produces "yyyy-MM-ddTHH:mm:ssZ" with literal Z and
  handles null safely (previous version would have produced "Z" alone
  for a null input thanks to string + null concatenation).

Both sides therefore agree on the canonical bytes for any datetime,
including across daylight savings transitions.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/api/routes/ValidateLicense.php

@@ -71,16 +71,22 @@ final class ValidateLicense
             )->execute([$lic['id'], $machineId, $machineLabel ?: null, $now, $now]);
         }
 
-        // Construit la réponse, signe-la, renvoie
-        $entUntil = (new \DateTimeImmutable($lic['download_entitlement_until']))->format(\DateTimeInterface::ATOM);
-        $serverTime = (new \DateTimeImmutable('now'))->format(\DateTimeInterface::ATOM);
+        // Construit la réponse, signe-la, renvoie.
+        // Tous les timestamps sont émis en UTC + format figé "yyyy-MM-ddTHH:mm:ssZ"
+        // pour que la canonicalisation côté client produise EXACTEMENT les mêmes bytes.
+        $utc = new \DateTimeZone('UTC');
+        $fmt = 'Y-m-d\TH:i:s\Z';
+
+        $issuedAt = (new \DateTimeImmutable($lic['issued_at'], $utc))->format($fmt);
+        $entUntil = (new \DateTimeImmutable($lic['download_entitlement_until'], $utc))->format($fmt);
+        $serverTime = (new \DateTimeImmutable('now', $utc))->format($fmt);
         $expired = strtotime($lic['download_entitlement_until']) < time();
 
         $payload = [
             'status'                     => $expired ? 'expired' : 'valid',
             'licenseId'                  => 'lic_' . $lic['id'],
             'ownerName'                  => $lic['owner_name'],
-            'issuedAt'                   => (new \DateTimeImmutable($lic['issued_at']))->format(\DateTimeInterface::ATOM),
+            'issuedAt'                   => $issuedAt,
             'downloadEntitlementUntil'   => $entUntil,
             'maxMachines'                => (int)$lic['max_machines'],
             'serverTime'                 => $serverTime,

server/tools/config.example.php

@@ -0,0 +1,43 @@
+<?php
+// === À RENSEIGNER LORS DU DÉPLOIEMENT ===
+// Copier ce fichier en config.php sur le serveur, puis le compléter.
+// Le fichier config.php est gitignored.
+
+return [
+    // Base path public sous lequel le launcher est servi
+    'base_url' => 'https://asterionvr.com/PS_Launcher',
+
+    // MySQL (depuis le manager OVH : Hébergements -> Bases de données)
+    'db' => [
+        // Format DSN OVH typique : mysql:host=<bdd>.mysql.db;dbname=<bdd>;charset=utf8mb4
+        'dsn'      => 'mysql:host=localhost;dbname=replace_me;charset=utf8mb4',
+        'username' => 'replace_me',
+        'password' => 'replace_me',
+    ],
+
+    // HMAC secret pour les URLs présignées de /builds/ (v0.6, optionnel)
+    // Génère 64 hex chars : `php -r "echo bin2hex(random_bytes(32));"`
+    'hmac_secret' => 'replace_with_random_64_bytes_hex',
+
+    // Clés Ed25519 pour signer la réponse de validation license et le manifest.
+    // Génère le keypair via : `php tools/generate-keypair.php`
+    // Recopie les hex strings ci-dessous, et embarque la public_key_hex dans le launcher.
+    'ed25519' => [
+        'private_key_hex' => '',  // 128 hex chars (sodium secret key, contient la pub key)
+        'public_key_hex'  => '',  // 64 hex chars (32 bytes)
+    ],
+
+    // (v0.4-β) JWT pour les URLs de download protégées (optionnel pour le moment)
+    'jwt_secret' => 'replace_with_random_secret',
+    'jwt_ttl_seconds' => 900, // 15 min
+
+    // Limites de validation
+    'validate_max_per_minute_per_ip' => 10,
+
+    // === BACKOFFICE ADMIN ===
+    // Mot de passe bcrypt pour la connexion à /PS_Launcher/admin/
+    // Génère le hash via SSH OVH :
+    //   php -r "echo password_hash('motdepasse_choisi', PASSWORD_DEFAULT);"
+    // puis colle le résultat ci-dessous.
+    'admin_password_hash' => '',
+];