v1.7.15 — i18n audit, splash min 3s, decimal precision, demo GIF, README fixes

- Complete i18n audit: 25+ new translation keys (en/it/de) — vacuum toast,
  TTS voices, timer steps, product notes, error prefixes, form placeholders,
  barcode hints, recipe/cooking ingredient labels, unit variants
- pz/conf unit labels now use t('units.pz') / t('units.conf') throughout
- Splash screen: minimum 3-second display (_splashStart recorded at parse
  time, fade delayed by remaining ms if app loads faster)
- Quantity decimal precision: qtyNum in recipe/cooking buttons and conf
  fallback display capped to 1 decimal (was showing 7+ from raw AI output)
- Recipe/cooking buttons: removed Italian fallback strings from t() calls
- README: translated remaining Italian phrases; added demo.gif to Screenshots
- CHANGELOG: updated 1.7.15 entry with all session changes
- assets/img/demo.gif: EverShelf.gif processed at 2x speed (~36s)

assets/css/style.css

@@ -104,10 +104,17 @@ body {
     letter-spacing: 0.5px;
 }
 .app-preloader-logo {
-    height: 120px;
+    height: 160px;
     width: auto;
     object-fit: contain;
-    filter: drop-shadow(0 2px 8px rgba(0,0,0,0.4));
+    filter: drop-shadow(0 4px 16px rgba(74,222,128,0.2));
+}
+.app-preloader-version {
+    color: rgba(255,255,255,0.35);
+    font-size: 0.72rem;
+    font-family: monospace;
+    letter-spacing: 0.5px;
+    margin-top: -8px;
 }
 .header-logo-icon {
     height: 28px;
@@ -1267,6 +1274,16 @@ body.server-offline .bottom-nav {
     color: white;
 }
 
+#btn-report-bug {
+    background: #f97316;
+    color: #fff;
+    border-color: #ea580c;
+}
+#btn-report-bug:hover {
+    background: #ea580c;
+    border-color: #c2410c;
+}
+
 .btn-secondary {
     background: var(--bg-card);
     color: var(--text);