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/main.css

@@ -2,6 +2,9 @@
 @import url("./base/variables.css");
 
 @import url("./base/reset.css");
+@import url("./base/typography.css");
+@import url("./base/animations.css");
+@import url("./base/a11y.css");
 @import url("./base/forms.css");
 
 /* Layout */
@@ -10,6 +13,7 @@
 @import url("./layout/content.css");
 
 /* Components */
+@import url("./components/brandLogo.css");
 @import url("./components/breadcrumb.css");
 @import url("./components/buttons.css");
 @import url("./components/fileType.css");
@@ -32,10 +36,12 @@
 @import url("./components/languageSelector.css");
 @import url("./components/batchToolbar.css");
 @import url("./components/spinner.css");
+@import url("./components/skeleton.css");
 @import url("./components/search.css");
 @import url("./components/icons.css");
 @import url("./components/csp-utilities.css");
 @import url("./components/itemTooltip.css");
+@import url("./components/commandPalette.css");
 
 /* Theme */
 @import url("./themes/dark.css");