refactor(tui): tighten editor handoff helpers

- editor.ts: collapse two private helpers into one flatMap-driven lookup,
  keep `isExecutable` as the only named primitive, document the fallback
  chain with prompt_toolkit parity
- editor.test.ts: hoist the `exe` helper out of `describe`, drop the
  empty afterEach + dead mkdir branch, materialize expected paths before
  the resolveEditor call so argument evaluation order doesn't bite
- useComposerState.openEditor: rmSync the mkdtemp dir (was leaking),
  early-return on bad exit / empty buffer, run cleanup in finally
- useInputHandlers: cheap `ch.toLowerCase() === 'g'` guard before the
  modifier check
- hermes-ink/screen.ts: pick up `npm run fix` import-sort cleanup so
  lint passes

ui-tui/src/app/useComposerState.ts

@@ -255,27 +255,34 @@ export function useComposerState({
   )
 
   const openEditor = useCallback(async () => {
-    const editor = resolveEditor()
-    const file = join(mkdtempSync(join(tmpdir(), 'hermes-')), 'prompt.md')
-    let code: null | number = null
+    const dir = mkdtempSync(join(tmpdir(), 'hermes-'))
+    const file = join(dir, 'prompt.md')
 
     writeFileSync(file, [...inputBuf, input].join('\n'))
 
+    let exitCode: null | number = null
+
     await withInkSuspended(async () => {
-      code = spawnSync(editor, [file], { stdio: 'inherit' }).status
+      exitCode = spawnSync(resolveEditor(), [file], { stdio: 'inherit' }).status
     })
 
-    if (code === 0) {
+    try {
+      if (exitCode !== 0) {
+        return
+      }
+
       const text = readFileSync(file, 'utf8').trimEnd()
 
-      if (text) {
-        setInput('')
-        setInputBuf([])
-        submitRef.current(text)
+      if (!text) {
+        return
       }
-    }
 
-    rmSync(file, { force: true })
+      setInput('')
+      setInputBuf([])
+      submitRef.current(text)
+    } finally {
+      rmSync(dir, { force: true, recursive: true })
+    }
   }, [input, inputBuf, submitRef])
 
   const actions = useMemo(

ui-tui/src/app/useInputHandlers.ts

@@ -366,10 +366,9 @@ export function useInputHandlers(ctx: InputHandlerContext): InputHandlerResult {
       return voiceRecordToggle()
     }
 
-    // Alt+G is the escape hatch for terminals that swallow Ctrl+G — VSCode and
-    // Cursor bind it to "Find Next" by default, so the keystroke never reaches
-    // the embedded TUI. Alt+G arrives as `\x1bg` → meta+g across platforms.
-    if (isAction(key, ch, 'g') || (key.meta && ch.toLowerCase() === 'g')) {
+    // Ctrl+G, plus Alt+G fallback for VSCode/Cursor (they bind Ctrl+G to
+    // "Find Next" before the TUI sees it; Alt+G arrives as meta+g).
+    if (ch.toLowerCase() === 'g' && (isAction(key, ch, 'g') || key.meta)) {
       return cActions.openEditor()
     }