indicate system prompt override on bottom right; require GEMINI_SYSTEM_MD to make it more explicit; allow custom paths for read/write (#427)

packages/cli/src/ui/components/Footer.tsx

@@ -74,6 +74,9 @@ export const Footer: React.FC<FooterProps> = ({
           <Text color={Colors.AccentRed}>▼ </Text>
         </Text>
       )}
+      {process.env.GEMINI_SYSTEM_MD && (
+        <Text color={Colors.AccentRed}>|⌐■_■|</Text>
+      )}
     </Box>
   </Box>
 );