Add Images admin section for managing source image uses

New top-level nav section showing all source images in a list view
with checkboxes to edit the uses array (grid, bin) per image. Allows
correcting wrongly-tagged images without code changes.

Server PUT /api/source-images/:id was already in place; re-added the
frontend API wrapper that was prematurely removed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/style.css

@@ -1844,6 +1844,68 @@ nav {
 	text-decoration: underline;
 }
 
+/* ===== IMAGES ADMIN ===== */
+
+.img-admin-list {
+	display: flex;
+	flex-direction: column;
+	gap: 0;
+}
+
+.img-admin-row {
+	display: flex;
+	align-items: center;
+	gap: 0.75rem;
+	padding: 0.5rem 0;
+	border-bottom: 1px solid var(--border);
+}
+
+.img-admin-thumb-link {
+	flex-shrink: 0;
+}
+
+.img-admin-thumb {
+	width: 80px;
+	height: 56px;
+	object-fit: cover;
+	border-radius: 3px;
+	display: block;
+}
+
+.img-admin-info {
+	flex: 1;
+	min-width: 0;
+	display: flex;
+	flex-direction: column;
+	gap: 0.2rem;
+}
+
+.img-admin-name {
+	font-size: 0.9rem;
+	overflow: hidden;
+	text-overflow: ellipsis;
+	white-space: nowrap;
+}
+
+.img-admin-meta {
+	font-size: 0.75rem;
+	color: var(--text-faint);
+}
+
+.img-admin-uses {
+	display: flex;
+	gap: 0.75rem;
+}
+
+.img-admin-use-label {
+	font-size: 0.8rem;
+	color: var(--text-muted);
+	cursor: pointer;
+	display: flex;
+	align-items: center;
+	gap: 0.25rem;
+}
+
 /* ===== BINS ===== */
 
 .bin-gallery {