docs: address mara review on #1936

- Drop the redundant 'including the root/bootstrap container' /
  'sub-agents + root' enumerations in the port-range + state-dir
  uniformity statements — 'every agent' / 'all agents' is enough (and
  calling out '+ root' reintroduces the special-case framing).
- Stop describing the root agent's privileged (manager-flavour) socket
  as a current thing (it's being removed): drop the conventions.md
  capability clause, the network.md per-agent-privileged-socket list
  entry, and the persistence.md /run/hyperhive/manager/mcp.sock
  runtime-dir bullet.

docs/persistence.md

@@ -189,7 +189,7 @@ Under `/var/lib/hyperhive/agents/<name>/`:
   `/home/<name>/.claude` inside the container.
 - `state/` — durable notes and `hyperhive-harness.json`. Bind-mounted
   to `/agents/<name>/state` inside the container (uniform for
-  all agents — sub-agents + root). The `$HYPERHIVE_STATE_DIR` env var exposes
+  all agents). The `$HYPERHIVE_STATE_DIR` env var exposes
   the same path to in-container scripts. Notable files written here
   by the harness:
   - `hyperhive-status` — single-line free-text status string written
@@ -323,9 +323,7 @@ Without that, every restart wipes bind sources and existing
 containers can't be started.
 
 - `/run/hyperhive/host.sock` — admin socket (host-side CLI).
-- `/run/hyperhive/manager/mcp.sock` — the root agent's privileged
-  (manager-flavour) socket.
-- `/run/hyperhive/agents/<name>/mcp.sock` — per-sub-agent socket
+- `/run/hyperhive/agents/<name>/mcp.sock` — per-agent socket
   (bind-mounted into the container as `/run/hive/mcp.sock`).
 
 On startup, `Coordinator::register_agent` drops any prior socket