fix(tui): restore macOS copy behavior and theme polish (#17131)

This PR groups the TUI fixes that restore macOS Terminal usability and clean up the theme/composer regressions:

- copy transcript selections on macOS drag-release so Terminal.app users can copy while mouse tracking is enabled
- copy composer selections on macOS drag-release; composer selection is internal to TextInput and does not use the global Ink selection bus
- keep IDE Cmd+C forwarding setup macOS-only, and make keybinding conflict checks respect simple when-clause overlap/negation
- force truecolor before chalk initializes (unless NO_COLOR / FORCE_COLOR / HERMES_TUI_TRUECOLOR opt-outs apply) so the default banner keeps its gold/amber/bronze gradient in Terminal.app
- move TUI surfaces onto semantic theme tokens and preserve skin prompt symbols as bare tokens with renderer-owned spacing
- render focused placeholders as dim hint text in TTY mode instead of inverse/selected-looking synthetic cursor text

ui-tui/src/components/todoPanel.tsx

@@ -9,7 +9,7 @@ import type { TodoItem } from '../types.js'
 const rowColor = (t: Theme, status: TodoItem['status']) => {
   const tone = todoTone(status)
 
-  return tone === 'active' ? t.color.cornsilk : tone === 'body' ? t.color.statusFg : t.color.dim
+  return tone === 'active' ? t.color.text : tone === 'body' ? t.color.statusFg : t.color.muted
 }
 
 export const TodoPanel = memo(function TodoPanel({
@@ -56,16 +56,16 @@ export const TodoPanel = memo(function TodoPanel({
   return (
     <Box flexDirection="column" marginBottom={1}>
       <Box onClick={handleToggle}>
-        <Text color={t.color.dim}>
-          <Text color={t.color.amber}>{effectiveCollapsed ? '▸ ' : '▾ '}</Text>
-          <Text bold color={t.color.cornsilk}>
+        <Text color={t.color.muted}>
+          <Text color={t.color.accent}>{effectiveCollapsed ? '▸ ' : '▾ '}</Text>
+          <Text bold color={t.color.text}>
             Todo
           </Text>{' '}
           <Text color={t.color.statusFg} dim>
             ({done}/{todos.length})
           </Text>
           {incomplete && pending > 0 && (
-            <Text color={t.color.dim} dim>
+            <Text color={t.color.muted} dim>
               {' '}
               · incomplete · {pending} still {pending === 1 ? 'pending' : 'pending/in_progress'}
             </Text>