fix(cli): surface pending interactive prompts

[devswha]

Summary

• add an authenticated, exact-target endpoint for a bounded plain-text tmux pane tail
• poll it only while a local CLI is waiting for its first transcript
• render trust, permission, and other interactive TUI prompts above the existing relay composer

Root cause

Fresh Codex, Claude, and Cursor sessions could stop at workspace-trust or command-approval prompts, but ChatMux's pending transcript surface only displayed generic guidance. Users could send selections but could not see which selection the CLI requested.

Safety

• validates the tmux name and verifies that it is currently a supported local CLI session
• uses an exact tmux target
• captures only the last 80 lines
• strips control bytes and caps the response at 32 KiB

Verification

• external session service tests (28/28)
• pending-output component tests (2/2)
• npm run typecheck
• npm run lint
• npm run build

[devswha]

E2E QA evidence (2026-07-22): the pending Codex session showed bounded live terminal output and the interactive TUI/version instead of an empty row.