refactor: tighten sidebars with eyebrow section headers

Compact the left/right sidebars and the photo info panel: shrink panel
widths, drop header height, switch top-level tree groups and metadata
sections to small uppercase eyebrow labels, and tighten row padding,
icon sizes, and count badges throughout.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/App.tsx

@@ -56,7 +56,7 @@ function App() {
         {/* Left Sidebar */}
         <div
           className={`transition-all duration-200 ${
-            leftSidebarOpen ? 'w-64' : 'w-0'
+            leftSidebarOpen ? 'w-60' : 'w-0'
           } overflow-hidden border-r border-border bg-surface`}
         >
           <LeftSidebar
@@ -88,7 +88,7 @@ function App() {
         {/* Right Sidebar */}
         <div
           className={`transition-all duration-200 ${
-            showRightSidebar ? 'w-80' : 'w-0'
+            showRightSidebar ? 'w-72' : 'w-0'
           } overflow-hidden border-l border-border bg-surface`}
         >
           <RightSidebar onCollapse={() => setRightSidebarOpen(false)} />