feat(po): drop periodic fleet sweep — operator-driven, recover-if-dead only

The PO's job is to manage projects on request, not watch them live. Remove the
hourly wake/sweep entirely:

- agents.toml: watch="heal" (recover-if-dead), no `wake` field
- prompts/supervise.md: deleted
- prompts/orchestrator.md, README.md, docs/bootstrap.md, docs/manage-projects.md:
  drop sweep/wake references; document operator-driven, no periodic sweep

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

README.md

@@ -10,7 +10,7 @@ is no special "control-plane" code path.
 project-orchestrator/
   agents.toml          this project's harness config (one persistent fleet-management agent)
   engine/              the agent-orchestrator harness, pinned as a submodule @ v0.1.0
-  prompts/             the PO agent's role (orchestrator.md) + periodic sweep (supervise.md)
+  prompts/             the PO agent's role (orchestrator.md)
   fleet.toml           THE fleet registry — the only record of project ↔ harness ↔ ref ↔ location
   scripts/             fleet.py + create/start/stop/update-project.sh — the management helpers
   docs/                runbooks: manage-projects.md, fleet-registry.md, bootstrap.md
@@ -41,9 +41,10 @@ python3 engine/agents.py up                   # start the PO agent + its watchdo
 python3 engine/agents.py down                 # stop everything
 ```
 
-The PO agent itself is one persistent `claude` session (`prompts/orchestrator.md`) with an hourly
-fleet sweep (`prompts/supervise.md`), supervised by the harness watchdog. See `engine/README.md`
-for the full harness reference.
+The PO agent itself is one persistent `claude` session (`prompts/orchestrator.md`), kept alive by the
+harness watchdog (recover-if-dead) but **never** woken on a timer: it is operator-driven and manages
+projects on request rather than watching them live. See `engine/README.md` for the full harness
+reference.
 
 ## Managing the fleet