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/fpsOverlay.tsx

@@ -5,23 +5,25 @@ import { useStore } from '@nanostores/react'
 
 import { SHOW_FPS } from '../config/env.js'
 import { $fpsState } from '../lib/fpsStore.js'
+import type { Theme } from '../theme.js'
 
-const fpsColor = (fps: number) => (fps >= 50 ? 'green' : fps >= 30 ? 'yellow' : 'red')
+const fpsColor = (fps: number, t: Theme) =>
+  fps >= 50 ? t.color.statusGood : fps >= 30 ? t.color.statusWarn : t.color.error
 
-export function FpsOverlay() {
+export function FpsOverlay({ t }: { t: Theme }) {
   if (!SHOW_FPS) {
     return null
   }
 
-  return <FpsOverlayInner />
+  return <FpsOverlayInner t={t} />
 }
 
-function FpsOverlayInner() {
+function FpsOverlayInner({ t }: { t: Theme }) {
   const { fps, lastDurationMs, totalFrames } = useStore($fpsState)
 
   // Zero-pad widths so digit churn doesn't jitter the corner.
   return (
-    <Text color={fpsColor(fps)}>
+    <Text color={fpsColor(fps, t)}>
       {fps.toFixed(1).padStart(5)}fps · {lastDurationMs.toFixed(1).padStart(5)}ms · #{totalFrames}
     </Text>
   )