Dashboard: Replace automatic banner rotation with random initial display and manual arrows

Replace the automatic timed banner rotation with a random initial banner
selection and small, manually operated arrow buttons for navigation.
Previous behavior can be restored by setting BannerRotation.automaticRotationEnabled to true.

The original slides used position:absolute + opacity for transitions.
This was changed to display:none/block because absolutely positioned
children don't contribute to their parent container's dimensions, causing
the banner containers to collapse to zero width/height. The arrow buttons
(position:absolute, top:50%) need a parent with real dimensions to
center correctly. With display:none/block, the active slide determines
the container's natural size.

The fixed height:60px on .gold-banner was removed for the same reason —
it clipped banner images that are taller than 60px.

An explicit height was added to .header-banner to ensure the arrow
buttons can vertically center via top:50% within the platinum banner area.

src/serena/resources/dashboard/dashboard.css

@@ -207,6 +207,7 @@ body {
     top: 0;
     left: 0;
     order: 2;
+    height: var(--header-height);
     max-height: var(--header-height);
 }
 
@@ -311,17 +312,13 @@ body {
 }
 
 .platinum-banner-slide {
-    position: absolute;
-    top: 0;
-    left: 0;
+    display: none;
     pointer-events: none;
     height: 100%;
-    opacity: 0;
-    transition: opacity 0.5s ease-in-out;
 }
 
 .platinum-banner-slide.active {
-    opacity: 1;
+    display: block;
     pointer-events: auto;
 }
 
@@ -351,19 +348,16 @@ body {
 .gold-banner {
     position: relative;
     width: 100%;
-    height: 60px;
     overflow: hidden;
 }
 
 .gold-banner-slide {
-    position: absolute;
+    display: none;
     pointer-events: none;
-    opacity: 0;
-    transition: opacity 0.5s ease-in-out;
 }
 
 .gold-banner-slide.active {
-    opacity: 1;
+    display: block;
     pointer-events: auto;
 }
 
@@ -372,6 +366,43 @@ body {
     object-fit: contain;
 }
 
+/* Banner Arrow Navigation */
+.banner-arrow {
+    position: absolute;
+    top: 50%;
+    transform: translateY(-50%);
+    z-index: 10;
+    background: rgba(128, 128, 128, 0.15);
+    color: var(--text-muted);
+    border: none;
+    font-size: 18px;
+    line-height: 1;
+    width: 24px;
+    height: 32px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    cursor: pointer;
+    border-radius: 4px;
+    opacity: 0.3;
+    transition: opacity 0.2s ease, background-color 0.2s ease, color 0.2s ease;
+    padding: 0;
+}
+
+.banner-arrow:hover {
+    opacity: 0.8;
+    background: rgba(128, 128, 128, 0.4);
+    color: var(--text-primary);
+}
+
+.banner-arrow-left {
+    left: 0;
+}
+
+.banner-arrow-right {
+    right: 0;
+}
+
 .page-view {
     /*max-width: 1600px;*/
     margin: 0 auto;

src/serena/resources/dashboard/dashboard.js

@@ -52,8 +52,17 @@ function updateThemeAwareImage($img, theme=null) {
     }
 }
 
+/**
+ * Manages banner loading, display, and navigation.
+ *
+ * When automaticRotationEnabled is true, banners rotate on a timer and arrow
+ * buttons are hidden.  When false (the current default), a random initial
+ * banner is shown and the user navigates manually via arrow buttons.
+ */
 class BannerRotation {
     constructor() {
+        this.automaticRotationEnabled = false;
+
         this.platinumIndex = 0;
         this.goldIndex = 0;
         this.platinumTimer = null;
@@ -67,8 +76,18 @@ class BannerRotation {
     init() {
         let self = this;
         this.loadBanners(function() {
-            self.startPlatinumRotation();
-            self.startGoldRotation();
+            self.randomizeInitialBanner('platinum');
+            self.randomizeInitialBanner('gold');
+
+            if (self.automaticRotationEnabled) {
+                self.startPlatinumRotation();
+                self.startGoldRotation();
+                // Hide arrows entirely when rotation is automatic
+                $('.banner-arrow').hide();
+            } else {
+                self.hideArrowsIfSingle();
+                self.bindArrowButtons();
+            }
         });
     }
 
@@ -119,6 +138,23 @@ class BannerRotation {
         }, this.platinumInterval);
     }
 
+    randomizeInitialBanner(type) {
+        const slideClass = type === 'platinum' ? '.platinum-banner-slide' : '.gold-banner-slide';
+        const $slides = $(slideClass);
+        const total = $slides.length;
+
+        if (total === 0) return;
+
+        const randomIndex = Math.floor(Math.random() * total);
+        if (type === 'platinum') {
+            this.platinumIndex = randomIndex;
+        } else {
+            this.goldIndex = randomIndex;
+        }
+        $slides.removeClass('active');
+        $slides.eq(randomIndex).addClass('active');
+    }
+
     startGoldRotation() {
         const self = this;
         this.goldTimer = setInterval(() => {
@@ -126,6 +162,30 @@ class BannerRotation {
         }, this.goldInterval);
     }
 
+    hideArrowsIfSingle() {
+        if ($('.platinum-banner-slide').length <= 1) {
+            $('#platinum-banners .banner-arrow').hide();
+        }
+        if ($('.gold-banner-slide').length <= 1) {
+            $('#gold-banners .banner-arrow').hide();
+        }
+    }
+
+    bindArrowButtons() {
+        let self = this;
+        $('.banner-arrow').on('click', function(e) {
+            e.preventDefault();
+            e.stopPropagation();
+            const target = $(this).data('target');
+            const direction = $(this).hasClass('banner-arrow-right') ? 'next' : 'prev';
+            if (target === 'platinum') {
+                self.rotatePlatinum(direction);
+            } else {
+                self.rotateGold(direction);
+            }
+        });
+    }
+
     rotatePlatinum(direction) {
         const $slides = $('.platinum-banner-slide');
         const total = $slides.length;
@@ -145,9 +205,11 @@ class BannerRotation {
         // Add active class to new slide
         $slides.eq(this.platinumIndex).addClass('active');
 
-        // Reset timer
-        clearInterval(this.platinumTimer);
-        this.startPlatinumRotation();
+        // Reset timer when in automatic rotation mode
+        if (this.automaticRotationEnabled) {
+            clearInterval(this.platinumTimer);
+            this.startPlatinumRotation();
+        }
     }
 
     rotateGold(direction) {
@@ -169,9 +231,11 @@ class BannerRotation {
         // Add active class to new group
         $groups.eq(this.goldIndex).addClass('active');
 
-        // Reset timer
-        clearInterval(this.goldTimer);
-        this.startGoldRotation();
+        // Reset timer when in automatic rotation mode
+        if (this.automaticRotationEnabled) {
+            clearInterval(this.goldTimer);
+            this.startGoldRotation();
+        }
     }
 }
 

src/serena/resources/dashboard/index.html

@@ -26,6 +26,8 @@
 
         <!-- Platinum Banners in Header -->
         <div id="platinum-banners" class="header-banner">
+            <button class="banner-arrow banner-arrow-left" data-target="platinum" aria-label="Previous banner">&#8249;</button>
+            <button class="banner-arrow banner-arrow-right" data-target="platinum" aria-label="Next banner">&#8250;</button>
         </div>
     </div>
 
@@ -147,6 +149,8 @@
 
                 <!-- Gold Banners -->
                 <section id="gold-banners" class="gold-banners-section">
+                    <button class="banner-arrow banner-arrow-left" data-target="gold" aria-label="Previous banner">&#8249;</button>
+                    <button class="banner-arrow banner-arrow-right" data-target="gold" aria-label="Next banner">&#8250;</button>
                 </section>
             </div>
         </div>