Add cc-ci-upgrader agent: observable one-shot weekly upgrade-run agent

The weekly upgrade run now executes inside a dedicated, remote-control agent
(cc-ci-upgrader) — viewable/steerable at claude.ai/code like the Builder — rather
than buried in headless cron output.

- launch-upgrader.sh: spins up the cc-ci-upgrader tmux session under
  --remote-control with a kickoff that runs /upgrade-all (DEFAULT mode) to
  completion. On finish the agent STOPS and stays idle (does NOT self-terminate)
  so the run + summary stay reviewable in the web UI. `start` = use-or-create:
  leaves an in-flight (busy) run alone, else clears a finished/idle/wedged
  session and runs fresh; `fresh` always restarts. UPGRADER_ARGS passes flags
  (e.g. --dry-run); never --with-tests.
- launch.sh: orchestrator_alive() now also skips the cc-ci-upgrader
  remote-control name, so the upgrader job isn't mistaken for the orchestrator.
- upgrade-all skill: documents it runs as the cc-ci-upgrader agent; the weekly
  cron invokes `launch-upgrader.sh start` (not /upgrade-all inline).
- Phase 5: V8a verifies the agent lifecycle (launch → run to completion → stay
  idle/viewable → next start clears it); V9 stops the verification session.
- cron memory: weekly task = launch-upgrader.sh start at 0 3 * * 6 UTC.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.claude/skills/upgrade-all/SKILL.md

@@ -12,6 +12,14 @@ recipe, and writes one summary of every PR to review. It **never pushes upstream
 
 Drives cc-ci over `ssh cc-ci`. Logs/summary go to `/srv/cc-ci/.cc-ci-logs/upgrades/`.
 
+**Runs as the `cc-ci-upgrader` agent.** This skill is normally executed by a dedicated, observable
+**one-shot job agent** — `cc-ci-upgrader` — spun up under remote-control (viewable/steerable at
+claude.ai/code, like the Builder) by `cc-ci-plan/launch-upgrader.sh`. That agent runs this skill to
+completion, then **stops and stays idle** so the run + summary remain reviewable in the web UI (it does
+NOT self-terminate). The weekly cron just invokes `launch-upgrader.sh start`; the next week's run
+clears the idle session and starts fresh. You can also run `/upgrade-all` inline in any `/srv/cc-ci`
+session, but the agent is the intended path so the weekly run isn't buried in headless output.
+
 ## Arguments (optional `$ARGUMENTS`)
 - A space-separated list of recipe names → only those (else all enrolled recipes).
 - `--dry-run` → survey + print what WOULD upgrade; spawn nothing.
@@ -104,16 +112,18 @@ End with the report path and a reminder that **nothing was merged**.
 - **Never merges**; failures/ skips are surfaced and retried next week — safe to re-run anytime.
 
 ## Cron
-Designed for a weekly Claude Code scheduled task that invokes `/upgrade-all` in `/srv/cc-ci`.
+Designed for a weekly Claude Code scheduled task that runs **`cc-ci-plan/launch-upgrader.sh start`** —
+which spins up the `cc-ci-upgrader` remote-control agent to run this skill to completion (the agent
+then stays idle/viewable). The cron does NOT invoke `/upgrade-all` inline.
 
 **Agreed schedule:** **Saturday 03:00 UTC** (`0 3 * * 6`) — low-traffic weekend window, PRs waiting by
 Monday.
 
 **Activation trigger (operator, 2026-05-29):** do NOT activate while the build loops are still
 constructing cc-ci — it would contend with them for the shared host. **Activate this weekly cron only
-once the cc-ci build is complete (loops finished / cc-ci stable.)** Until then it's run manually /
-on-demand. When activating, create a scheduled task that runs `/upgrade-all` in `/srv/cc-ci` at
-`0 3 * * 6` UTC.
+once the cc-ci build is complete (loops finished / cc-ci stable.)** Until then run it manually /
+on-demand via `launch-upgrader.sh start` (or `fresh`). When activating, create a scheduled task that
+runs `/srv/cc-ci/cc-ci-plan/launch-upgrader.sh start` at `0 3 * * 6` UTC.
 
 Re-running is idempotent: already-current recipes report `SKIPPED — up-to-date`; recipes with an open
 PR for the same branch report the existing PR rather than duplicating it.