refactor(#1865): consolidate agent + manager socket servers into one

The per-agent and manager sockets ran two parallel dispatchers with
duplicated lifecycle handlers (agent-side topology-gated, manager-side
ungated) plus a manager-only handler set. Collapse to one parameterized
server in socket_server.rs:

- one serve() + dispatch(req, agent, privileged, coord); start() binds
  the per-agent sockets (privileged=false), start_manager() binds the
  manager socket (privileged=true).
- each lifecycle/config handler (start/restart/kill/update/init_config/
  apply_commit) merges its dual: the topology guard (require_child /
  require_new_child) runs only on the !privileged path; init_config
  records the requester as parent only when !privileged. restart keeps
  the orthogonal, capability-gated + audited infra-container branch.
- the agent-state queries (loose-ends / reminder count + rollup) branch
  on privileged: privileged keeps any-target + the "*" hive-wide sweep
  (query_agent_state-gated), non-privileged keeps the topology/cap gate.
- the privileged-only verbs (schedules / meta-inputs / get_logs) plus
  the submit/schedule/watchdog helpers move into socket_server; they are
  reached via dispatch_privileged_only(), which rejects the whole group
  on a non-privileged socket.
- delete manager_server.rs; repoint refs; merge the test modules.

No behavior change: the topology guard still applies on every
non-privileged lifecycle call, the privileged socket still acts on any
agent, and privileged-only verbs are still rejected on agent sockets.

hive-c0re/src/dashboard/lifecycle_ops.rs

@@ -76,7 +76,7 @@ pub(super) async fn post_kill(
     // host-side approval queue without the manager up, and
     // operator-driven meta-input updates work from the dashboard
     // either way. The MCP-surface self-kill guard in
-    // `manager_server.rs::ManagerRequest::Kill` stays in place: a
+    // `socket_server.rs::ManagerRequest::Kill` stays in place: a
     // manager calling Kill on its own container is self-suicide
     // mid-call, not a legitimate operator action.
     state.coord.rebuild_queue.enqueue(

hive-c0re/src/dashboard/schedules.rs

@@ -21,7 +21,7 @@ pub(super) async fn api_schedules(State(state): State<AppState>) -> Response {
         Ok(rows) => {
             let mut wire: Vec<hive_sh4re::WireSchedule> = rows
                 .into_iter()
-                .map(crate::manager_server::schedule_to_wire_public)
+                .map(crate::socket_server::schedule_to_wire_public)
                 .collect();
             // Drop ghost targets (agents that no longer exist) so the
             // table never shows dead columns. Uses the reliable async
@@ -33,7 +33,7 @@ pub(super) async fn api_schedules(State(state): State<AppState>) -> Response {
                 .into_iter()
                 .map(|c| c.name)
                 .collect();
-            crate::manager_server::filter_ghost_schedule_targets(&mut wire, &live);
+            crate::socket_server::filter_ghost_schedule_targets(&mut wire, &live);
             axum::Json(wire).into_response()
         }
         Err(e) => error_response(&format!("scheduled_prompts list: {e:#}")),
@@ -214,7 +214,7 @@ pub(super) async fn patch_schedule(
     }
     match state.coord.scheduled_prompts.get(id) {
         Ok(Some(s)) => {
-            let wire = crate::manager_server::schedule_to_wire_public(s);
+            let wire = crate::socket_server::schedule_to_wire_public(s);
             state.coord.emit_schedules_snapshot();
             axum::Json(wire).into_response()
         }