refactor: reduce UI spacing and dimensions throughout desktop client for more compact layout

Reduce padding, gaps, and font sizes across all components. Change html/body/root from min-height to fixed height with overflow hidden. Decrease app-frame padding from 18px to 12px and add grid-template-rows with overflow handling. Reduce brand lockup logo from 54px to 44px and adjust gaps throughout. Decrease button padding, surface padding, and card padding. Reduce body-grid sidebar from 290px to 250px.

desktop-client/src/App.tsx

@@ -299,7 +299,6 @@ export function App() {
                 <h4>Resources</h4>
               </div>
             </div>
-            <p className="access-hint">Press <strong>Sync</strong> after policy changes.</p>
             <ul className="resource-stack">
               {(state?.resources ?? ["No resources assigned yet"]).map((resource) => (
                 <li key={resource}>{resource}</li>