Add support for multiple images from Twitter links

- Fetch all images from Twitter syndication API (photos array)
- Store images with unified 'image' media type (first = thumbnail by ID order)
- Display multi-image tweets in grid layout on detail page
- Add hover cycling through images on home grid (2s interval)
- Show image count indicator on multi-image items
- Extract shared downloadAndStoreImages() helper for create/refresh
- Add migration to convert existing thumbnail/gallery types to image
- Make images clickable to open in new tab on detail page

internal/static/css/app.css

@@ -599,6 +599,66 @@ input[type="file"] {
 	color: var(--gray-3);
 }
 
+/* Image Gallery (detail page) */
+.image-gallery {
+	display: grid;
+	grid-template-columns: repeat(2, 1fr);
+	gap: 2px;
+}
+
+.image-gallery img {
+	width: 100%;
+	height: auto;
+	display: block;
+	cursor: pointer;
+	transition: opacity 0.15s ease;
+}
+
+.image-gallery img:hover {
+	opacity: 0.9;
+}
+
+/* Single image when odd count - make last one full width */
+.image-gallery img:last-child:nth-child(odd) {
+	grid-column: span 2;
+}
+
+/* Gallery Cycling (home grid) */
+.grid-item-images {
+	position: relative;
+	width: 100%;
+}
+
+.grid-item-images img {
+	width: 100%;
+	display: block;
+	position: absolute;
+	top: 0;
+	left: 0;
+	opacity: 0;
+	transition: opacity 0.4s ease;
+}
+
+.grid-item-images img:first-child {
+	position: relative;
+}
+
+.grid-item-images img.active {
+	opacity: 1;
+}
+
+/* Gallery Indicator */
+.gallery-indicator {
+	position: absolute;
+	top: 0.5rem;
+	right: 0.5rem;
+	background: rgba(0, 0, 0, 0.7);
+	color: #fff;
+	font-size: 0.7rem;
+	padding: 0.2rem 0.4rem;
+	pointer-events: none;
+}
+
 /* Responsive */
 @media (max-width: 1200px) {
 	.grid {