hive-ag3nt: scrub mcp.rs cookies (#716 batch 8)

Last #716 hotspot — scrub-only batch. All substantive prose is
already documented in docs/turn-loop.md::MCP surface (Sub-agent
tools, Manager tools, Tool whitelist, Tool envelope), so the 10
cookies in mcp.rs come out without prose extraction.

- format_agent_meta rustdoc: drop #432 attribution, add docs pointer
  for the running=false / status_text-stale rationale
- get_agent_meta hive/swarm comment: drop #710 attribution
- AgentServer + ManagerServer add-tool warnings: drop #511 attribution
  twice (kept the lockstep invariant)
- edit_schedule description: drop #474 + #478 cookies in user-facing
  tool text
- cancel_loose_end description: drop #250 cookie in user-facing text
- Manager allow-list block: drop the long #444/#235/#467/#472/#474/
  #478/#509 attribution roll, keep the lockstep invariant
- check_send_allowed (<parent> branch): drop #692, replace with the
  actual semantics ("falls back to operator for root agents")
- prompts/system.md: drop #474 cookie from edit_schedule line
- Cargo.toml [[bin]]: drop #598 pre-/post- split history, add docs
  pointer to docs/turn-loop.md::Harness binary shape

cargo check + 56 tests pass.
Closes #716 (last cookie hotspot).

hive-ag3nt/prompts/system.md

@@ -23,7 +23,7 @@ Tools (hyperhive surface):
 - `mcp__hyperhive__request_schedule_prompt(targets, body, first_fire_at_unix, interval_seconds?, description?)` — queue an approval for the operator to add a scheduled prompt. On approve hive-c0re inserts a schedule row and the worker fans `body` out to each agent in `targets` at `first_fire_at_unix` (recurring every `interval_seconds` if set, one-shot when absent). Even self-targeted schedules go through approval — the existing `remind` tool stays the quick no-approval self-wake path. Catch-up clamp: long downtime fires ONCE per recurring row on resume (skipped count surfaces in per-target `last_result`), not N stacked pulses.
 - `mcp__hyperhive__cancel_schedule(id, targets?)` — cancel a schedule. Omit `targets` / pass empty to cancel the whole schedule; pass a list to cancel just those recipients (the schedule keeps firing for any remaining active targets, auto-cancels when every target is gone). Authorization: you can cancel schedules you own OR any owned by a sub-agent in your subtree per topology.json.
 - `mcp__hyperhive__fire_schedule_now(id)` — fire a scheduled prompt out of band. Runs the per-target fan-out once immediately. Recurring schedules keep their cadence intact (the manual fire is additive); one-shot schedules are CONSUMED by the manual fire (cancelled afterwards). Same authorization as `cancel_schedule`.
-- `mcp__hyperhive__edit_schedule(id, body?, description?, interval_seconds?, next_fire_at_unix?, targets_add?, targets_remove?)` — partial-update a schedule's mutable fields (#474). Pass only the fields you want to change. `targets_add` / `targets_remove` mutate the recipient list in the same transaction; re-adding a previously-cancelled target drops the tombstone + history (operator intent: "fresh start"). Refuses cancelled rows. Same authorization as `cancel_schedule`. Note: clearing scalar fields (e.g. flipping recurring→one-shot) is operator-only via the dashboard PATCH — the agent surface only supports positive sets on `description` / `interval_seconds`.
+- `mcp__hyperhive__edit_schedule(id, body?, description?, interval_seconds?, next_fire_at_unix?, targets_add?, targets_remove?)` — partial-update a schedule's mutable fields. Pass only the fields you want to change. `targets_add` / `targets_remove` mutate the recipient list in the same transaction; re-adding a previously-cancelled target drops the tombstone + history (operator intent: "fresh start"). Refuses cancelled rows. Same authorization as `cancel_schedule`. Note: clearing scalar fields (e.g. flipping recurring→one-shot) is operator-only via the dashboard PATCH — the agent surface only supports positive sets on `description` / `interval_seconds`.
 - `mcp__hyperhive__list_schedules()` — snapshot every schedule in the queue (active + cancelled-but-not-reaped). Returns id, owner, body, target set with per-target `last_fired_at` + `last_result`, `next_fire_at_unix`, recurring `interval_seconds`. Use to look up an id before cancelling, or to audit upcoming wake-ups across the swarm.
 - `mcp__hyperhive__get_logs(agent, lines?)` — fetch recent journal lines for a sub-agent container. Use to diagnose MCP-server registration failures, startup crashes, or harness issues you can't see from inside. Pass the plain logical agent name; `lines` defaults to 50 (capped at 500).
 <!-- /role:manager -->