Fix: SW Network-First für Navigation + versionierte CSS/JS-URLs (v=32)

- sw.js: index.html nie aus Cache (navigation → network-first)
- index.html: ?v=32 an layout.css, components.css, api/ui/app.js
- sw.js STATIC_ASSETS: versionierte URLs gecacht
- app.js: Sidebar-Background per getComputedStyle statt CSS-Variable-String
- SW by-v31 → by-v32

backend/static/js/app.js

@@ -196,17 +196,20 @@ const App = (() => {
     const sidebar = document.getElementById('sidebar');
     if (!sidebar) return;
     // Inline-Styles: unabhängig vom CSS-Cache-Stand
+    // Inline-Styles: unabhängig vom CSS-Cache; Farben als Fallback hardcoded
+    const bg = getComputedStyle(document.documentElement)
+                  .getPropertyValue('--c-surface').trim() || '#ffffff';
     sidebar.style.cssText = [
       'display:flex',
       'position:fixed',
       'top:0', 'left:0', 'bottom:0',
       'width:240px',
       'z-index:2000',
-      'background:var(--c-surface,#fff)',
+      `background:${bg}`,
       'flex-direction:column',
       'overflow:hidden',
       'box-shadow:4px 0 24px rgba(0,0,0,0.22)',
-      'border-right:1px solid var(--c-border-light,#eee)',
+      'border-right:1px solid #e5e7eb',
     ].join(';');
     document.getElementById('sidebar-backdrop')?.classList.add('visible');
   }