feat(ui): UI-002 Command Palette und Deep-Links statt Nav-Umbau

Globale Suche/Quick Actions per Strg/Cmd+K (CommandPalette): Objekt-
Suche nach Name/Code, Sprung zu QR-Scan/Material/Lager/Personal/
Verwaltung. AdminPage-Tab jetzt im URL-Query (?tab=...) statt nur
lokalem State, damit die Palette gezielt verlinken kann, ohne Routen
zu duplizieren. Bewusst keine neuen Sidebar-Punkte fuer Fahrzeuge/
Kontrollen/Pruefungen - dafuer gibt es keine eigenstaendigen Listen-
Seiten in MABEA.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CVgbozhYmuEhiEJHffRXCV

frontend/src/styles/global.css

@@ -462,6 +462,61 @@ select.input:focus {
   color: var(--color-text);
 }
 
+/* UI-002 (Epic 20): Command Palette (Ctrl/Cmd+K) */
+.command-palette-overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(10, 14, 20, 0.5);
+  display: flex;
+  align-items: flex-start;
+  justify-content: center;
+  padding-top: 12vh;
+  z-index: 200;
+}
+
+.command-palette {
+  width: min(90vw, 32rem);
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius);
+  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.25);
+  padding: 0.75rem;
+}
+
+.command-palette-list {
+  list-style: none;
+  margin: 0.5rem 0 0;
+  padding: 0;
+  max-height: 60vh;
+  overflow-y: auto;
+}
+
+.command-palette-empty {
+  padding: 0.6rem 0.5rem;
+}
+
+.command-palette-item {
+  width: 100%;
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  gap: 0.5rem;
+  background: none;
+  border: none;
+  text-align: left;
+  padding: 0.55rem 0.5rem;
+  border-radius: var(--radius-sm);
+  font-size: 0.95rem;
+  color: var(--color-text);
+  cursor: pointer;
+  font-family: inherit;
+}
+
+.command-palette-item:hover,
+.command-palette-item:focus-visible {
+  background: var(--color-surface-sunken);
+}
+
 .alert {
   border-radius: var(--radius-sm);
   padding: 0.75rem 1rem;