chore(tui): /clean pass — inline one-off locals, tighten ConfirmPrompt

- providers.ts: drop the `dup` intermediate, fold the ternary inline
- paths.ts (fmtCwdBranch): inline `b` into the `tag` template
- prompts.tsx (ConfirmPrompt): hoist a single `lower = ch.toLowerCase()`,
  collapse the three early-return branches into two, drop the
  redundant bounds checks on arrow-key handlers (setSel is idempotent
  at 0/1), inline the `confirmLabel`/`cancelLabel` defaults at the
  use site
- modelPicker.tsx / config/env.ts / providers.test.ts: auto-formatter
  reflows picked up by `npm run fix`
- useInputHandlers.ts: drop the stray blank line that was tripping
  perfectionist/sort-imports (pre-existing lint error)

ui-tui/src/domain/paths.ts

@@ -10,8 +10,7 @@ export const fmtCwdBranch = (cwd: string, branch: null | string, max = 40) => {
     return shortCwd(cwd, max)
   }
 
-  const b = branch.length > 16 ? `…${branch.slice(-15)}` : branch
-  const tag = ` (${b})`
+  const tag = ` (${branch.length > 16 ? `…${branch.slice(-15)}` : branch})`
 
   return `${shortCwd(cwd, Math.max(8, max - tag.length))}${tag}`
 }