feat: progress bar startup check with 29 diagnostics (v1.7.21)

- Replace banner checklist with real-time progress bar + per-check label
  Bar fills smoothly (0→100%) as each check runs; label shows current check.
  On success: bar stays green briefly then fades. On warnings: amber badges
  shown for 2.2s. On critical error: bar turns red + error block + Retry.
- Extend health_check to 29 comprehensive checks:
  PHP 8.0+ version, 4 critical extensions (pdo_sqlite/curl/json/mbstring),
  4 optional extensions (openssl/fileinfo/zip/intl), PHP memory/timeout/upload,
  data/ writable, rate_limits/ dir, backups/ dir, actual file-write test,
  free disk space, SQLite connect, required tables, PRAGMA quick_check integrity,
  WAL mode, DB file size, inventory row count, .env file, Gemini AI key,
  Bring! credentials + token, cURL SSL version, internet reachability (Gemini API)
- Fresh-install detection: if dispensa.db not found + data/ writable → OK (auto-create)
- Translations: startup.* expanded to 28 keys in IT, EN, DE, FR, ES
- CSS: new .preloader-progress-wrap, .preloader-bar-track, .preloader-bar,
  .preloader-check-label, .preloader-warn-badge; removed old .preloader-checks
- Version: v1.7.21, assets v=20260520b

assets/css/style.css

@@ -116,41 +116,72 @@ body {
     letter-spacing: 0.5px;
     margin-top: -8px;
 }
-/* ── Startup health check list ─────────────────────────────────────── */
-.preloader-checks {
+/* ── Startup progress bar ───────────────────────────────────────────── */
+.preloader-progress-wrap {
     display: flex;
     flex-direction: column;
-    gap: 6px;
-    width: 240px;
-    max-width: 90vw;
+    align-items: center;
+    gap: 10px;
+    width: 250px;
+    max-width: 88vw;
+    animation: zwFadeIn 0.2s ease;
+}
+.preloader-bar-track {
+    width: 100%;
+    height: 6px;
+    background: rgba(255,255,255,0.12);
+    border-radius: 99px;
+    overflow: hidden;
+}
+.preloader-bar {
+    height: 100%;
+    width: 0%;
+    background: linear-gradient(90deg, #4ade80, #22c55e);
+    border-radius: 99px;
+    transition: width 0.18s ease, background 0.3s ease;
+}
+.preloader-bar.bar-error { background: linear-gradient(90deg, #f87171, #ef4444); }
+.preloader-bar.bar-warn  { background: linear-gradient(90deg, #fbbf24, #f59e0b); }
+.preloader-check-label {
+    color: rgba(255,255,255,0.60);
+    font-size: 0.74rem;
+    font-family: monospace;
+    text-align: center;
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    max-width: 100%;
+    min-height: 1.1em;
+    letter-spacing: 0.01em;
+}
+.preloader-warnings {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 5px;
+    justify-content: center;
+    max-width: 270px;
     animation: zwFadeIn 0.25s ease;
 }
-.preloader-check-row {
-    display: flex;
-    align-items: center;
-    gap: 8px;
-    font-size: 0.82rem;
-    color: rgba(255,255,255,0.80);
-    background: rgba(255,255,255,0.07);
-    border-radius: 8px;
-    padding: 5px 10px;
-    transition: background 0.2s;
+.preloader-warn-badge {
+    background: rgba(251,191,36,0.15);
+    color: #fcd34d;
+    border: 1px solid rgba(251,191,36,0.35);
+    border-radius: 99px;
+    padding: 3px 10px;
+    font-size: 0.71rem;
+    white-space: nowrap;
 }
-.preloader-check-row[data-state="ok"]    { background: rgba(74,222,128,0.10); color: rgba(255,255,255,0.92); }
-.preloader-check-row[data-state="warn"]  { background: rgba(251,191,36,0.12); color: rgba(255,255,255,0.92); }
-.preloader-check-row[data-state="error"] { background: rgba(239,68,68,0.15);  color: #fca5a5; }
-.pck-icon  { font-size: 1rem; line-height: 1; flex-shrink: 0; }
-.pck-label { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
 .preloader-error-msg {
     color: #fca5a5;
     background: rgba(239,68,68,0.18);
     border: 1px solid rgba(239,68,68,0.4);
     border-radius: 10px;
-    padding: 10px 16px;
-    font-size: 0.88rem;
+    padding: 12px 18px;
+    font-size: 0.84rem;
     text-align: center;
     max-width: 280px;
-    line-height: 1.4;
+    line-height: 1.5;
+    white-space: pre-line;
     animation: zwFadeIn 0.3s ease;
 }
 .preloader-retry-btn {