fix(header): full redesign — left-aligned title, uniform buttons, update badge

- Title always left-aligned (was centered via 3-col flex trick)
- In kiosk mode: exit/refresh buttons appear left of title via header-left
- All action buttons unified as .header-btn (42×42px, consistent style)
- Scan button: 48×48px + pulse animation to stand out from others
- Gemini button: no longer misuses header-scan-btn class; own indigo tint
- Scale status: same 42×42px .header-btn shape with colored .scale-dot
  inside instead of a tiny 22px standalone circle
- Update notification: uses #header-update-badge beside the title instead
  of replacing title innerHTML (title never disappears anymore)
- Fixed _scaleUpdateStatus() to preserve header-btn class on className reset

index.html

@@ -61,14 +61,29 @@
 <!-- Top Header -->
 <header class="app-header">
     <div class="header-content">
+        <!-- Kiosk buttons (exit / refresh) — injected here by _injectKioskOverlay() -->
         <div class="header-left" id="header-left"></div>
-        <h1 class="header-title" onclick="showPage('dashboard')"><span data-i18n="nav.title">🏠 EverShelf</span><span class="header-version">v1.6.0</span></h1>
+
+        <!-- Title — left-aligned; grows to fill space -->
+        <div class="header-title-wrap">
+            <h1 class="header-title" onclick="showPage('dashboard')">
+                <span data-i18n="nav.title">🏠 EverShelf</span><span class="header-version">v1.6.0</span>
+            </h1>
+            <!-- Update badge — shown alongside title, never replaces it -->
+            <span class="header-update-badge" id="header-update-badge" style="display:none"></span>
+        </div>
+
+        <!-- Actions — fixed set of icon buttons, all same size -->
         <div class="header-actions">
-            <span id="scale-status-indicator" class="scale-status-indicator scale-status-disconnected" style="display:none" data-i18n-title="scale.status_disconnected" title="⚖️ Bilancia">⚖️</span>
-            <button class="header-scan-btn header-gemini-btn" onclick="showPage('chat')" title="Chat con Gemini" data-i18n-title="chat.title">
-                <svg class="gemini-icon" viewBox="0 0 24 24" width="28" height="28" fill="white"><path d="M12 0C12 6.627 6.627 12 0 12c6.627 0 12 5.373 12 12 0-6.627 5.373-12 12-12-6.627 0-12-5.373-12-12z"/></svg>
+            <button id="scale-status-indicator" class="header-btn scale-status-indicator scale-status-disconnected"
+                    style="display:none" data-i18n-title="scale.status_disconnected" title="⚖️ Bilancia">
+                <span class="scale-dot"></span>
             </button>
-            <button class="header-scan-btn" id="btn-header-scan" title="Scansiona prodotto (tieni premuto per modalità spesa)" data-i18n-title="scan.hint">
+            <button class="header-btn header-gemini-btn" onclick="showPage('chat')" title="Chat con Gemini" data-i18n-title="chat.title">
+                <svg class="gemini-icon" viewBox="0 0 24 24" width="24" height="24" fill="white"><path d="M12 0C12 6.627 6.627 12 0 12c6.627 0 12 5.373 12 12 0-6.627 5.373-12 12-12-6.627 0-12-5.373-12-12z"/></svg>
+            </button>
+            <button class="header-btn header-scan-btn" id="btn-header-scan"
+                    title="Scansiona prodotto (tieni premuto per modalità spesa)" data-i18n-title="scan.hint">
                 📷
             </button>
         </div>