feat(app): refine agent profile creation (#3680)

Keep profiles as the richer primitive while restoring the familiar star cue and clearer guidance for agent selection. Account for borders in shared field geometry so controls preserve their declared heights across form consumers.

packages/app/src/agent-profiles/internal/agent-profile-glyph.tsx

@@ -1,7 +1,6 @@
 import { withUnistyles } from "react-native-unistyles";
 import {
   BookOpen,
-  Bot,
   Boxes,
   Brain,
   Bug,
@@ -27,6 +26,7 @@ import {
   Server,
   Shield,
   Sparkles,
+  Star,
   Terminal,
   TestTube,
   Wrench,
@@ -42,7 +42,7 @@ import {
 } from "./profile-appearance";
 
 /** Drawn when a profile names no icon, and as the "default" cell in the picker grid. */
-const ThemedDefaultIcon = withUnistyles(Bot);
+const ThemedDefaultIcon = withUnistyles(Star);
 
 /**
  * `withUnistyles` has to wrap each icon once at module scope, so the registry