fix(tui): raise picker selection contrast with inverse + bold

Selected rows in the model/session/skills pickers and approval/clarify
prompts only changed from dim gray to cornsilk, which reads as low
contrast on lighter themes and LCDs (reported during TUI v2 blitz).

Switch the selected row to `inverse bold` with the brand accent color
across modelPicker, sessionPicker, skillsHub, and prompts so the
highlight is terminal-portable and unambiguous. Unselected rows stay
dim. Also extends the sessionPicker middle meta column (which was
always dim) to inherit the row's selection state.

ui-tui/src/__tests__/useComposerState.test.ts

@@ -1,11 +1,15 @@
-import { describe, expect, it, vi } from 'vitest'
+import { describe, expect, it } from 'vitest'
 
 import { looksLikeDroppedPath } from '../app/useComposerState.js'
 
 describe('looksLikeDroppedPath', () => {
   it('recognizes macOS screenshot temp paths and file URIs', () => {
-    expect(looksLikeDroppedPath('/var/folders/x/T/TemporaryItems/Screenshot\\ 2026-04-21\\ at\\ 1.04.43 PM.png')).toBe(true)
-    expect(looksLikeDroppedPath('file:///var/folders/x/T/TemporaryItems/Screenshot%202026-04-21%20at%201.04.43%20PM.png')).toBe(true)
+    expect(looksLikeDroppedPath('/var/folders/x/T/TemporaryItems/Screenshot\\ 2026-04-21\\ at\\ 1.04.43 PM.png')).toBe(
+      true
+    )
+    expect(
+      looksLikeDroppedPath('file:///var/folders/x/T/TemporaryItems/Screenshot%202026-04-21%20at%201.04.43%20PM.png')
+    ).toBe(true)
   })
 
   it('rejects normal multiline or plain text paste', () => {