feat(operator): Phase 6 — relay-mode read (screen) + stop-condition engine (watch)

Completes the remote-drive triad for a broker-owned sandbox the operator can't
exec into directly: keys (in) → watch (wait) → screen (out).

- _sbx:data PTY-relay frames are absorbed into a capped rolling terminal buffer
  (not surfaced as chat); `screen` returns it ansi-stripped (or raw). sandbox.
  strip_ansi handles CSI/OSC/CR noise so output greps cleanly.
- `watch` is a formal stop-condition engine: blocks until a regex matches in the
  screen buffer or chat events, or an idle-quiescence window, or a hard timeout,
  then reports which fired — the autonomy loop's principled wait.
- Skill doctrine updated with the type→wait→read relay loop.

28 offline tests green.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/hh-operator/SKILL.md

@@ -72,12 +72,18 @@ $HH sbx down                                            # tear your container do
 When the **room** has a sandbox and you're granted, `exec`/`write`/`get` target
 it directly (you're co-located on the host) — no launch needed.
 
-**Keystroke relay** — drive the room's *shared* terminal live, like a human:
+**Keystroke relay** — drive the room's *shared* terminal live, like a human.
+The relay loop is **type → wait → read**:
 ```bash
-$HH keys "ls -la" enter          # type + run
-$HH keys ctrl-c                  # interrupt the running program
-$HH keys --help-keys             # print the full vocabulary
+$HH keys "make build" enter             # type + run
+$HH watch --for "BUILD (SUCCESS|FAIL)" --in screen --timeout 120   # wait
+$HH screen                               # read the relayed terminal (ansi-stripped)
+$HH keys ctrl-c                          # interrupt the running program
+$HH keys --help-keys                     # print the full vocabulary
 ```
+`watch` is the stop-condition engine — it blocks until a regex matches (in
+`screen` output or chat `events`), or `--idle N` quiet, or `--timeout` — then
+reports which fired. This is how you stay autonomous without busy-polling.
 
 ### Keystroke cheat-sheet (how to *stop* things matters most)