docs: align the cron, teammate-pane and TUI comments with the paste

- cron resolvePrompt(): give the reason the rest of the cron docs give (the
  submit check cannot recognise a multi-line paste; in paste mode the newlines
  reach the CLI as keys) instead of the old one about writeViaMux fusing lines.
- sendInputToPane(): it types with send-keys -l and strips line breaks, so it
  no longer uses "the same approach as sendInput()".
- TUI client: newlines become spaces (the docstring said stripped), and the
  test name no longer cites "multi-line breaks Ink".

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/tmux-manager.ts

@@ -4019,7 +4019,9 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
 
   /**
    * Send input to a specific pane within a tmux session.
-   * Uses the same literal text approach as sendInput() but targets a specific pane.
+   * Types the text literally with `send-keys -l`, line breaks stripped, then Enter
+   * when the input carried a `\r`. Unlike sendInput(), it neither pastes nor keeps
+   * the line breaks of multi-line text.
    */
   sendInputToPane(muxName: string, paneTarget: string, input: string): boolean {
     if (IS_TEST_MODE) return true;