Rebrand remaining user-visible Grok strings to Kigi/Kimi

The welcome hero subtitle still read "Thanks for trying Grok Build";
theme display names, the NO_COLOR/COLORTERM diagnostics notes, the
permission notification title, the self-update restart hints, and the
clipboard-wrap protocol marker all still said Grok. Canonical theme keys
(groknight/grokday) are unchanged — only display strings move.

crates/codegen/kigi-tui/src/diagnostics.rs

@@ -640,7 +640,7 @@ pub fn color_support_warning(
             None,
             None,
         );
-        warning.note = Some("Unset NO_COLOR and restart Grok.".to_string());
+        warning.note = Some("Unset NO_COLOR and restart Kigi.".to_string());
         return Some(warning);
     }
 
@@ -677,7 +677,7 @@ pub fn color_support_warning(
         Some("export COLORTERM=truecolor"),
         None,
     );
-    warning.note = Some("Persist in ~/.zshrc / ~/.bashrc and restart Grok.".to_string());
+    warning.note = Some("Persist in ~/.zshrc / ~/.bashrc and restart Kigi.".to_string());
     Some(warning)
 }