add legal page editor integration and media library polish

Legal pages (privacy, delivery, terms) now auto-populate content from
shop settings on mount, show auto-generated vs customised badges, and
have a regenerate button. Theme editor gains alt text fields for logo,
header, and icon images. Image picker in page builder now has an upload
button and alt text warning badges. Clearing unused image references
shows an orphan info flash.

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

assets/css/admin/components.css

@@ -1869,6 +1869,7 @@
 }
 
 .image-picker-item {
+  position: relative;
   display: flex;
   flex-direction: column;
   align-items: center;
@@ -1927,6 +1928,38 @@
   font-size: 0.8125rem;
 }
 
+.image-picker-upload {
+  margin-bottom: 0.75rem;
+}
+
+.image-picker-upload-label {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 0.5rem;
+  padding: 0.5rem;
+  border: 1px dashed var(--t-border-default);
+  border-radius: 0.375rem;
+  font-size: 0.8125rem;
+  cursor: pointer;
+  color: color-mix(in oklch, var(--t-text-primary) 60%, transparent);
+  transition: border-color 100ms, color 100ms;
+
+  @media (hover: hover) {
+    &:hover {
+      border-color: var(--t-text-primary);
+      color: var(--t-text-primary);
+    }
+  }
+}
+
+.image-picker-item-no-alt {
+  color: var(--t-warning, #f59e0b);
+  position: absolute;
+  top: 0.25rem;
+  right: 0.25rem;
+}
+
 /* ═══════════════════════════════════════════════════════════════════
    Media library
    ═══════════════════════════════════════════════════════════════════ */