feat: photo/video capture-date pipeline + premium UI/UX overhaul

Backend — Photos timeline now groups by real capture date instead of upload time. New MediaMetadataService (FileLifecycleHook) extracts EXIF DateTimeOriginal from images and container creation_time from videos (mov/mp4/mkv) via nom-exif, timezone-correct (OffsetTimeOriginal), persisting captured_at so the existing media_sort_date trigger takes over. Adds POST /admin/photos/metadata/reextract to backfill existing media. Falls back to upload date when no embedded date exists.

Frontend — premium grid cards: combined metadata line (relative date · size, owner avatar when shared), custom selection checkbox with a clear checked state, uniform full-width 4:3 thumbnail tiles independent of filename length, centered file-type icons, and a hit-test fix so checkbox/star/kebab clicks reach the controls (the decorative thumbnail no longer captures pointer events). Notification messages internationalised across all 16 locales. Broader polish: design tokens, a11y/focus-visible states, brand + PWA assets.

Chore — bump semver-compatible dependencies (cargo upgrade); add nom-exif 3.6.1.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

static/css/components/csp-utilities.css

@@ -2,9 +2,10 @@
 
 /* ── Empty state icons (large, muted) ── */
 .empty-state-icon {
-    font-size: 48px;
-    color: var(--color-border-ddd);
-    margin-bottom: 16px;
+    font-size: var(--text-6xl);
+    color: var(--color-accent);
+    margin-bottom: var(--space-4);
+    opacity: 0.9;
 }
 .empty-state-icon.error {
     color: var(--color-danger-text-alt);
@@ -23,8 +24,8 @@
     margin-right: 5px;
 }
 .icon-ml {
-    margin-left: 4px;
-    font-size: 12px;
+    margin-left: var(--space-1);
+    font-size: var(--text-xs);
 }
 
 /* ── Success check icon ── */
@@ -34,9 +35,9 @@
 
 /* ── Move dialog ── */
 .move-dialog-hint {
-    margin: 0 0 12px;
+    margin: 0 0 var(--space-3);
     color: var(--color-text-muted);
-    font-size: 14px;
+    font-size: var(--text-base);
 }
 .folder-select-container {
     max-height: 220px;
@@ -50,7 +51,7 @@
 
 /* ── Search spinner ── */
 .search-spinner {
-    margin-right: 8px;
+    margin-right: var(--space-2);
 }
 
 /* ── Search empty state text ── */
@@ -60,7 +61,7 @@
 
 /* ── Notification upload current file ── */
 .notif-upload-current {
-    font-size: 11px;
+    font-size: var(--text-2xs);
     color: var(--color-text-subtle);
     margin: 3px 0;
     white-space: nowrap;
@@ -71,7 +72,7 @@
 /* ── Login auth hint ── */
 .auth-hint {
     color: var(--text-secondary, var(--color-text-medium));
-    margin-top: 4px;
+    margin-top: var(--space-1);
     display: block;
 }
 
@@ -81,7 +82,7 @@
 }
 .about-modal-header {
     text-align: center;
-    padding: 20px 20px 0;
+    padding: var(--space-5) var(--space-5) 0;
 }
 .about-modal-avatar {
     width: 64px;
@@ -92,27 +93,27 @@
     display: inline-flex;
     align-items: center;
     justify-content: center;
-    font-size: 24px;
-    font-weight: 700;
-    margin-bottom: 12px;
+    font-size: var(--text-2xl);
+    font-weight: var(--weight-bold);
+    margin-bottom: var(--space-3);
 }
 .about-modal-username {
     margin: 0;
-    font-size: 18px;
+    font-size: var(--text-lg);
     color: var(--color-text-navy);
 }
 .about-modal-email {
-    margin: 4px 0 0;
-    font-size: 13px;
+    margin: var(--space-1) 0 0;
+    font-size: var(--text-sm);
     color: var(--color-text-subtle);
 }
 .about-modal-role {
     display: inline-block;
-    margin-top: 8px;
-    padding: 2px 10px;
-    border-radius: 10px;
-    font-size: 11px;
-    font-weight: 600;
+    margin-top: var(--space-2);
+    padding: var(--space-0-5) var(--space-2-5);
+    border-radius: var(--radius-xl);
+    font-size: var(--text-2xs);
+    font-weight: var(--weight-semibold);
 }
 .about-modal-role-admin {
     background: var(--color-role-admin-bg);
@@ -123,48 +124,48 @@
     color: var(--color-text-subtle);
 }
 .about-modal-storage {
-    padding: 16px 20px;
+    padding: var(--space-4) var(--space-5);
 }
 .about-modal-storage-label {
-    font-size: 12px;
+    font-size: var(--text-xs);
     color: var(--color-text-subtle);
     text-transform: uppercase;
     letter-spacing: 0.05em;
-    margin-bottom: 6px;
+    margin-bottom: var(--space-1-5);
 }
 .about-modal-storage-label i {
-    margin-right: 4px;
+    margin-right: var(--space-1);
 }
 .about-modal-bar-bg {
     background: var(--color-border-light);
-    border-radius: 6px;
+    border-radius: var(--radius-md);
     height: 8px;
     overflow: hidden;
-    margin-bottom: 4px;
+    margin-bottom: var(--space-1);
 }
 .about-modal-bar-fill {
     height: 100%;
-    border-radius: 6px;
+    border-radius: var(--radius-md);
     transition: width 0.3s;
 }
 .about-modal-bar-text {
-    font-size: 12px;
+    font-size: var(--text-xs);
     color: var(--color-text-subtle);
     text-align: right;
 }
 .about-modal-footer {
-    padding: 0 20px 16px;
+    padding: 0 var(--space-5) var(--space-4);
     display: flex;
     justify-content: center;
 }
 .about-modal-close-btn {
-    padding: 8px 24px;
+    padding: var(--space-2) var(--space-6);
     border: 1px solid var(--color-border);
-    border-radius: 8px;
+    border-radius: var(--radius-lg);
     background: var(--color-bg-surface);
     color: var(--color-text-dark);
-    font-size: 13px;
-    font-weight: 600;
+    font-size: var(--text-sm);
+    font-weight: var(--weight-semibold);
     cursor: pointer;
     transition: background 0.15s;
 }