fix(kiosk): scale retry restores nav buttons + settings link to webapp

SetupActivity:
- btnTestRetry click handler: add step3NextButtons.visibility = VISIBLE
  so the Indietro/Avanti buttons reappear after pressing No-retry
  (previously they stayed hidden → user was stuck with no way to go back)
- onDisconnected(): always re-enable btnTestRetry so user is never stuck
  when scale drops unexpectedly before a weight reading arrives

SettingsActivity / activity_settings.xml:
- Add 'IMPOSTAZIONI AVANZATE' section explaining that HA, Gemini AI,
- Add '← Torna all'app per le impostazioni avanzate' button (finish())

evershelf-kiosk/app/src/main/kotlin/it/dadaloop/evershelf/kiosk/SettingsActivity.kt

@@ -123,6 +123,9 @@ class SettingsActivity : AppCompatActivity() {
         // Back
         findViewById<android.widget.ImageButton>(R.id.btnBack).setOnClickListener { finish() }
 
+        // Advanced settings → back to webapp (where HA, Gemini, Bring! etc. are configured)
+        findViewById<MaterialButton>(R.id.btnOpenAppSettings).setOnClickListener { finish() }
+
         // Test connection
         findViewById<MaterialButton>(R.id.btnTestConnection).setOnClickListener { testConnection() }
 

evershelf-kiosk/app/src/main/kotlin/it/dadaloop/evershelf/kiosk/SetupActivity.kt

@@ -400,6 +400,7 @@ class SetupActivity : AppCompatActivity() {
             scaleTestCard.visibility   = View.GONE
             testWeightBox.visibility   = View.GONE
             bleSetupCard.visibility    = View.VISIBLE
+            step3NextButtons.visibility = View.VISIBLE   // restore nav buttons (back/next)
             tvSelectedScale.text       = ""
             tvSelectedScale.visibility = View.GONE
             tvScanStatus.text          = getString(R.string.ble_not_confirmed)
@@ -960,6 +961,8 @@ class SetupActivity : AppCompatActivity() {
             testWeightBox.visibility = View.GONE
             testHasWeight = false
             findViewById<MaterialButton>(R.id.btnTestConfirm).isEnabled = false
+            // Always re-enable retry so the user is never stuck
+            findViewById<MaterialButton>(R.id.btnTestRetry).isEnabled = true
         }
         override fun onWeightReceived(reading: WeightReading) {
             if (!isInTestMode) return

evershelf-kiosk/app/src/main/res/layout/activity_settings.xml

@@ -224,6 +224,43 @@
             </LinearLayout>
         </LinearLayout>
 
+        <!-- Advanced / App Settings link -->
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:text="IMPOSTAZIONI AVANZATE"
+            android:textColor="#7c3aed"
+            android:textSize="12sp"
+            android:textStyle="bold"
+            android:letterSpacing="0.1"
+            android:layout_marginBottom="12dp" />
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:background="@drawable/card_background"
+            android:padding="16dp"
+            android:layout_marginBottom="24dp">
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="Home Assistant, Gemini AI, Bring!, TTS, notifiche e tutte le altre funzionalità si configurano direttamente nell'app EverShelf."
+                android:textColor="#94a3b8"
+                android:textSize="13sp"
+                android:layout_marginBottom="12dp" />
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/btnOpenAppSettings"
+                android:layout_width="match_parent"
+                android:layout_height="44dp"
+                android:text="← Torna all'app per le impostazioni avanzate"
+                android:textSize="13sp"
+                android:textAllCaps="false"
+                android:backgroundTint="#7c3aed" />
+        </LinearLayout>
+
         <!-- Danger Zone -->
         <TextView
             android:layout_width="match_parent"