docs(approvals): reframe stale 'the manager' as the root agent

The last docs/ piece of the manager-cleanup. The manager is no longer a
structural role — root-ness is purely topological. Reframe:
- title 'Approvals + manager + helper events' -> 'Approvals + helper events'
- section headers: 'Manager view of applied'/'Manager policy'/'Manager
  (ruth) is hive-c0re-managed'/'Helper events to the manager' ->
  root-agent / root-bootstrap-container equivalents
- body prose: 'the manager (ruth)' -> 'the root agent' (or 'the submitter'
  in the approval-flow steps)
- authority semantics: 'manager-only' -> approvals are submitted by an
  agent with the approvals tool group, for its direct children
- dropped the stale 'the manager refuses to destroy itself' line (the
  bootstrap container is now destroyable + transient; recreated on startup)

Kept the genuine code/protocol identifiers (nixosConfigurations.manager,
manager_server, role:manager prompt block, notify_manager, the
/run/hyperhive/manager/ socket path) — renaming those would diverge from
the source (de-hardcoding is its own backend cleanup).

docs/approvals.md

@@ -11,9 +11,12 @@ informed about what happens after a decision lands.
 ## End-to-end approval flow
 
 1. The submitting agent (the child's parent, holding the `approvals`
-   tool group) edits files under the child's `/agents/<name>/config/`
-   (any tracked path, but `agent.nix` is the contract entry point) and
-   commits with its own git identity.
+   tool group) edits files in the child's proposed config repo
+   (any tracked path, but `agent.nix` is the contract entry point)
+   and commits with its own git identity. The parent's container has
+   the child's proposed config repo bind-mounted read-write at
+   `/agents/<name>/config/` (topology-driven via `set_nspawn_flags`;
+   the agent's *own* config at `/agents/<self>/config/` is read-only).
 2. The submitting agent submits the commit sha via `request_apply_commit(agent,
    commit_ref)`. `commit_ref` must be a commit **sha** (7-40 hex
    chars, short or full) — a branch or tag name is rejected so the
@@ -88,7 +91,9 @@ without it has nothing of its own to withdraw.
 `InitConfig` approvals are the first step in a two-step spawn
 flow. On approve, hive-c0re seeds the proposed config repo with
 a default `agent.nix` template and sends `HelperEvent::ConfigReady { agent }`
-to the root agent. The submitting agent then reviews,
+to the root agent's inbox (current limitation — all helper events route
+to the root agent via `notify_manager` regardless of which agent
+submitted; tracked in #1953). The submitting agent then reviews,
 edits, and commits the template before calling `request_apply_commit`
 to proceed to an `ApplyCommit` approval. The first `ApplyCommit`
 creates the container; subsequent ones rebuild it with new config.
@@ -400,26 +405,32 @@ The dashboard deep-links into this org — a `config repo` link
 per container row and a `commit on forge` link per approval
 card. See `docs/web-ui.md`.
 
-### Root-agent view of applied + meta
+### Submitting agent's view of config repos
 
-The root agent container gets three host-side bind mounts via
-`set_nspawn_flags`:
+Every parent agent's container has its **direct children's** proposed
+config repos bind-mounted read-write (topology-driven: `lifecycle.rs`
+calls `bind_child_agent_dirs` for each entry in
+`topology::children_of(agent_name)`). An agent with the `approvals`
+tool group can therefore edit, commit, and submit changes for any of
+its direct children directly inside its container at `/agents/<child>/config/`.
 
-- `/var/lib/hyperhive/agents/` → `/agents/` (RW) — proposed
-  repos. The root agent edits + commits per-agent config here.
-- `/var/lib/hyperhive/applied/` → `/applied/` (RO) — every
-  agent's authoritative applied repo, including `.git`.
+Agents holding the `can_manage_top_level_agents` topology role get
+additional host-side bind mounts via `set_nspawn_flags`:
+
+- `/var/lib/hyperhive/agents/` → `/agents/` (RW) — all top-level
+  agents' proposed repos (not just direct children).
+- `/var/lib/hyperhive/applied/` → `/applied/` (RO) — every agent's
+  authoritative applied repo, including `.git`.
 - `/var/lib/hyperhive/meta/` → `/meta/` (RO) — the swarm-wide
   deploy flake.
 
-This is the **root agent's** view — RW over *every* agent's config. An
-agent with the `approvals` group that owns a subtree (a sub-manager) has
-the equivalent RW scoped to its own children's config repos.
+The root agent holds this role; a sub-manager that only manages a
+subtree does not, and only has its direct children's config dirs.
 
 Each proposed repo (`/agents/<n>/config/`) is pre-configured
 with `applied` as a git remote pointing at
-`/applied/<n>/.git`. Useful incantations from inside the
-root agent's container:
+`/applied/<n>/.git`. Useful incantations from inside an agent with
+the full `/applied` mount:
 
 ```sh
 git -C /agents/<n>/config fetch applied
@@ -433,9 +444,8 @@ git -C /meta log --oneline                                    # swarm-wide deplo
 cat /meta/flake.lock | jq '.nodes | with_entries(select(.key | startswith("agent-")))'
 ```
 
-The RO binds block push at the kernel level, so the root agent
-can only fetch / read — git plumbing inside the container
-cannot corrupt either authoritative repo.
+The RO binds block push at the kernel level — git plumbing inside the
+container cannot corrupt either authoritative repo.
 
 ## Migration from the pre-tag / pre-meta schemes
 
@@ -495,25 +505,25 @@ updates the root agent itself.
 
 ## Root-agent policy
 
-From `hive-ag3nt/prompts/system.md` (`<!-- role:manager -->` block,
-rendered via `hive_ag3nt::prompt::render`): the root agent does NOT
-rubber-stamp sub-agent config requests. It verifies (role match,
-package legitimacy, cheaper alternative, blast radius) before
-committing and calling `request_apply_commit`.
+The system prompt (`hive-ag3nt/prompts/system.md`, rendered via
+`hive_ag3nt::prompt::render`) is the **same for every agent**; what
+varies is which MCP tools are surfaced (gated by tool groups and
+capabilities in `agent.nix`). There is no `role:manager` block that
+renders only for the root agent. The root agent's approval-gating
+behaviour comes from its CLAUDE.md / agent-specific instructions, not
+the system prompt template.
 
-For ambiguous cases or anything that needs human signal, the
-the root agent calls `ask(question, options?, multi?, ttl_seconds?, to?)` —
-queues the question and returns the id immediately. When `to` is
-omitted (or `"operator"`) the question shows up on the dashboard;
-when `to` is a sub-agent's name, the recipient receives a
+`ask(question, options?, multi?, ttl_seconds?, to?)` is available to
+**any agent** — it queues a question and returns the id immediately.
+When `to` is omitted (or `"operator"`) the question shows up on the
+dashboard; when `to` is another agent's name, the recipient receives a
 `HelperEvent::QuestionAsked` and answers via their own `answer`
 tool. Either way the answer arrives back as
 `HelperEvent::QuestionAnswered { id, question, answer, answerer }`
 in the asker's inbox. Storage is `hive-c0re::operator_questions`
 (sqlite) — same table, with a nullable `target` column
 (NULL = operator). Dispatch goes through
-`hive-c0re/src/questions.rs::{handle_ask, handle_answer}` so both
-the agent + root-agent surfaces stay aligned. The answer flow is:
+`hive-c0re/src/questions.rs::{handle_ask, handle_answer}`. The answer flow is:
 
 ```
 POST /answer-question/{id}                       agent: Answer { id, answer }
@@ -526,7 +536,7 @@ POST /answer-question/{id}                       agent: Answer { id, answer }
 Two more paths resolve a pending question with a sentinel answer:
 
 - `POST /cancel-question/{id}` (✗ CANC3L button on the dashboard)
-  resolves with `[cancelled]`. The root agent sees a terminal state
+  resolves with `[cancelled]`. The asking agent sees a terminal state
   and can fall back.
 - `ttl_seconds` deadline: a tokio watchdog spawned at submit time
   fires `answer(id, "[expired]")` once the ttl runs out. Already-