image view: implement gallery-based layout, metadata dropdown, and thumbnails; add styles for image shadow; update tests

viewer/static/css/noscript.css

@@ -10,3 +10,8 @@
     width: 100% !important;
     flex: 0 0 auto !important;
 }
+
+/* Ensure image area still visible without JS */
+.image-wrapper {
+    max-width: 100%;
+}

viewer/static/css/styles.css

@@ -175,6 +175,32 @@ body {
     padding-bottom: 8px;
 }
 
+/* Image view specific styles */
+.image-content {
+    overflow: auto;
+    padding: 18px;
+}
+
+.image-wrapper {
+    display: inline-block;
+    max-width: calc(100% - 40px);
+    border-radius: 14px;
+    overflow: hidden;
+    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.35);
+}
+
+.image-full {
+    display: block;
+    max-width: 100%;
+    height: auto;
+    border-radius: 14px;
+}
+
+.info-menu {
+    min-width: 220px;
+    border-radius: 8px;
+}
+
 .thumb-card {
     width: 128px;
     display: block;