rename(#162): fix MANAGER_AGENT and @manager in docs

docs/agent-hierarchy.md

@@ -104,11 +104,10 @@ which axis the post-milestone version reads each special-case along:
 
 ### A — naming + bootstrap
 
-- `MANAGER_AGENT = "manager"` (broker recipient name) and
-  `MANAGER_NAME = "root"` (container name). ~28 grep hits across
-  `hive-c0re/src/`. **Just a name** — renamed from `hm1nd` to `root`
-  via the one-shot migration script in `migrate.rs` (idempotent,
-  marker-guarded).
+- `MANAGER_AGENT = "root"` (broker recipient name) and
+  `MANAGER_NAME = "root"` (container name). Both now `"root"`;
+  renamed from `"manager"`/`"hm1nd"` via the migration script in
+  `migrate.rs` (idempotent, marker-guarded).
 - `auto_update::ensure_manager` runs at hive-c0re boot and spawns
   `root` if missing. Becomes "ensure the root agent exists" once any
   agent can be at the root. **Topology**: root has no parent, so

docs/web-ui/dashboard.md

@@ -287,8 +287,7 @@ localStorage; auto-complete from the live container list, Tab/Enter
 to confirm; `@*` broadcasts). `POST /op-send` drops
 `{from:"operator", to, body}` into the broker; the resulting SSE
 frame re-renders both the terminal row and the inbox section.
-Manager is addressed as `@manager` (the broker recipient string),
-not `@root` (the container name).
+Manager is addressed as `@root`.
 
 ## Container row