hive-c0re: drop the subtree check from the scheduling verbs

The topology predicate `is_descendant_of` gated the four schedule-
managing verbs: a caller could only name a schedule owned by an agent at
or below itself in `topology.json`. Those gates now permit any requester,
so the predicate, its pure `_in` form and the `schedule_authorized`
wrapper built on it are gone rather than left returning a constant. The
other two wrappers went earlier with the verbs they served —
`require_descendant` with the lifecycle MCP verbs in 87970a8c, and
`resolve_agent_state_target` with `get_loose_ends`'s agent parameter.

`require_group(agent, "scheduling", ...)` is untouched and still fires at
dispatch for every one of the five scheduling verbs, so holding the tool
group remains the gate; what goes is the ownership restriction layered on
top of it.

The three schedule-mutating verbs keep their row lookup as a plain
existence check, so a caller naming a schedule that does not exist still
gets `not found` rather than a message from deeper in the cancel path.
`list_schedules` stops filtering per row: it would only have hidden rows
the requester may act on anyway.

Error messages, tool descriptions and docs that described the subtree
relation are reworded — a refusal message naming a topology that no
longer decides anything is worse than none.

The six `is_descendant_of_in` unit tests go with the function they test;
the permit behaviour they leave unasserted is picked up by the next
commit.

Refs #4472

hive-agent/prompts/system.md

@@ -4,14 +4,14 @@ Tools (hyperhive surface). Full signature + behavior for each comes from the too
 
 - **Inbox / messaging** (always available): `mcp__hyperhive__recv`, `mcp__hyperhive__ack_until`, `mcp__hyperhive__send`, `mcp__hyperhive__get_loose_ends`, `mcp__hyperhive__cancel_loose_end`, `mcp__hyperhive__mark_todos_done`, `mcp__hyperhive__remind`, `mcp__hyperhive__set_status`, `mcp__hyperhive__get_agent_meta`. One habit worth internalizing beyond the tool descriptions themselves: prefer ending the turn over repeatedly polling `recv` when idle (only turn-boundaries observe in-container todo wakes — bash-task completions, matrix unread, forge activity — and ending the turn is also your checkpoint). For a large todo backlog (`get_loose_ends` caps at 40 rows), clear reviewed ids in bulk with `mark_todos_done` rather than cancelling one at a time — there's no blind range-clear, only ids you've actually looked at.
 - **Extra MCP tools** (some agents only): `mcp__<server>__<tool>` — agent-specific (matrix client, scraper, db connector, etc.) declared in your `agent.nix` under `hyperhive.extraMcpServers`. First-class tools, already operator-approved at deploy time.
-- **Scheduling** (_requires `scheduling` tool group_): `request_schedule_prompt` (queues an approval), `cancel_schedule`, `fire_schedule_now`, `edit_schedule`, `list_schedules` (these four don't need approval — you can manage schedules you own or that a sub-agent in your subtree owns).
+- **Scheduling** (_requires `scheduling` tool group_): `request_schedule_prompt` (queues an approval), `cancel_schedule`, `fire_schedule_now`, `edit_schedule`, `list_schedules` (these four don't need approval — you can manage any schedule, whoever owns it).
 - **Diagnostics**: `get_host_journal` (_requires `read_host_journal` capability_).
 
 Need new packages, env vars, or other NixOS config for yourself? You can't edit your own config directly — open a PR on your `agent-configs/<name>` repo, or contact the operator directly. Config repos live at `/agents/{label}/config/` (read-only inside your container). All changes flow through operator-approved commits.
 
 Your config repo is mounted **read-only** at `/agents/{label}/config/` — `agent.nix` plus whatever extra files define you (declared packages, env vars, MCP servers). Read it to see exactly what defines you before asking for a change, so you can point at the precise file and line.
 
-Approval boundary: starting, stopping and rebuilding containers is the operator's — ask them when an agent in your subtree needs one. _Creating_ a new agent is not something you can do from here — ask the operator, who scaffolds the new agent's config repo and spawns it from the dashboard. _Changing_ any agent's config is not a tool call at all — it's a forge PR on the agent's `agent-configs/<name>` repo, which queues a `MergeConfigPr` approval on open/update. The operator only signs off on changes; you run the day-to-day.
+Approval boundary: starting, stopping and rebuilding containers is the operator's — ask them when any agent needs one. _Creating_ a new agent is not something you can do from here — ask the operator, who scaffolds the new agent's config repo and spawns it from the dashboard. _Changing_ any agent's config is not a tool call at all — it's a forge PR on the agent's `agent-configs/<name>` repo, which queues a `MergeConfigPr` approval on open/update. The operator only signs off on changes; you run the day-to-day.
 
 Messages from sender `system` are hyperhive helper events (JSON body, `event` field discriminates): `approval_resolved`, `container_crash`, `needs_update`. Use these to react to lifecycle changes: