fix: rounded icons, setup text overflow, new chat on model switch, token counts

1. Desktop icon: bake rounded corners into the PNG/ICNS/ICO so the icon
   looks consistent on Desktop and in Applications.
2. SetupScreen: truncate long status text with ellipsis, word-break
   error messages so they don't overflow the block.
3. Model switching: create a new chat session when changing models,
   preventing stale context errors with the new model.
4. X-Ray footer: show input/output token counts in the collapsed
   summary (e.g. "42 in · 128 out") alongside engine, model, latency.

frontend/src/components/Chat/XRayFooter.tsx

@@ -18,7 +18,9 @@ export function XRayFooter({ usage, telemetry }: Props) {
   const parts: string[] = [];
   if (telemetry?.engine) parts.push(telemetry.engine);
   if (telemetry?.model_id) parts.push(telemetry.model_id);
-  if (usage?.completion_tokens) parts.push(`${usage.completion_tokens} tok`);
+  if (usage && (usage.prompt_tokens || usage.completion_tokens)) {
+    parts.push(`${usage.prompt_tokens} in \u00B7 ${usage.completion_tokens} out`);
+  }
   if (telemetry?.total_ms) parts.push(formatMs(telemetry.total_ms));
 
   if (parts.length === 0 && !usage?.total_tokens) return null;

frontend/src/components/CommandPalette.tsx

@@ -70,9 +70,10 @@ export function CommandPalette() {
     setSelectedModel(modelId);
     setCommandPaletteOpen(false);
 
-    // Preload the model if switching to a different one
+    // Switching models creates a new chat session for a clean slate
     if (modelId !== previousModel) {
-      const { setModelLoading, addLogEntry } = useAppStore.getState();
+      const { createConversation, setModelLoading, addLogEntry } = useAppStore.getState();
+      createConversation(modelId);
       setModelLoading(true);
       addLogEntry({ timestamp: Date.now(), level: 'info', category: 'model', message: `Switching to ${modelId}...` });
       try {

frontend/src/components/SetupScreen.tsx

@@ -48,7 +48,7 @@ function StepRow({
         <div className="text-sm font-medium" style={{ color: 'var(--color-text)' }}>
           {label}
         </div>
-        <div className="text-xs" style={{ color: 'var(--color-text-tertiary)' }}>
+        <div className="text-xs truncate" style={{ color: 'var(--color-text-tertiary)', maxWidth: '280px' }}>
           {done ? 'Ready' : active ? detail : 'Waiting...'}
         </div>
       </div>
@@ -145,7 +145,7 @@ export function SetupScreen({ onReady }: { onReady: () => void }) {
             }}
           >
             <XCircle size={16} className="shrink-0 mt-0.5" />
-            <span>{status.error}</span>
+            <span style={{ wordBreak: 'break-word', overflowWrap: 'anywhere' }}>{status.error}</span>
           </div>
         )}