manager: add optional agent param to reminder RPCs

CountPendingReminders and ReminderRollup were hardcoded to
MANAGER_AGENT. Both now take agent: Option<String> — None keeps the
current behavior (manager's own), Some(name) returns that agent's
reminder stats. The broker functions already take an agent name, so
this is a thin wire-protocol change. Callers (web UI stats page,
post-turn counts) pass None.

Closes #122

hive-ag3nt/src/bin/hive-m1nd.rs

@@ -343,7 +343,7 @@ async fn fetch_manager_post_turn_counts(socket: &Path) -> (Option<u64>, Option<u
     };
     let reminders = match client::request::<_, ManagerResponse>(
         socket,
-        &ManagerRequest::CountPendingReminders,
+        &ManagerRequest::CountPendingReminders { agent: None },
     )
     .await
     {

hive-ag3nt/src/web_ui.rs

@@ -529,6 +529,8 @@ async fn fetch_reminder_stats(socket: &std::path::Path, flavor: Flavor, window_s
                 socket,
                 &hive_sh4re::ManagerRequest::ReminderRollup {
                     since_secs: window_secs,
+                    // Manager's own stats page — its own reminders.
+                    agent: None,
                 },
             )
             .await

hive-c0re/src/manager_server.rs

@@ -409,16 +409,18 @@ async fn dispatch(req: &ManagerRequest, coord: &Arc<Coordinator>) -> ManagerResp
                 },
             }
         }
-        ManagerRequest::CountPendingReminders => {
+        ManagerRequest::CountPendingReminders { agent } => {
-            match coord.broker.count_pending_reminders_for(MANAGER_AGENT) {
+            let target = agent.as_deref().unwrap_or(MANAGER_AGENT);
+            match coord.broker.count_pending_reminders_for(target) {
                 Ok(count) => ManagerResponse::PendingRemindersCount { count },
                 Err(e) => ManagerResponse::Err {
                     message: format!("{e:#}"),
                 },
             }
         }
-        ManagerRequest::ReminderRollup { since_secs } => {
+        ManagerRequest::ReminderRollup { since_secs, agent } => {
-            match coord.broker.reminder_rollup_for(MANAGER_AGENT, *since_secs) {
+            let target = agent.as_deref().unwrap_or(MANAGER_AGENT);
+            match coord.broker.reminder_rollup_for(target, *since_secs) {
                 Ok(stats) => ManagerResponse::ReminderRollup(stats),
                 Err(e) => ManagerResponse::Err {
                     message: format!("{e:#}"),

hive-sh4re/src/lib.rs

@@ -804,9 +804,13 @@ pub enum ManagerRequest {
         #[serde(default)]
         agent: Option<String>,
     },
-    /// Count of the manager's own pending reminders. Mirror of
+    /// Count of pending reminders. `agent` selects whose: `None` =
+    /// the manager's own, `Some("<name>")` = that agent's. Mirror of
     /// `AgentRequest::CountPendingReminders` on the manager surface.
-    CountPendingReminders,
+    CountPendingReminders {
+        #[serde(default)]
+        agent: Option<String>,
+    },
     /// Reminder statistics: counts of scheduled, delivered, and pending
     /// reminders (manager-flavour). Mirror of `AgentRequest::ReminderRollup`.
     ReminderRollup {
@@ -814,6 +818,10 @@ pub enum ManagerRequest {
         /// Pass 0 to include all reminders.
         #[serde(default)]
         since_secs: u64,
+        /// Whose reminders to roll up: `None` = the manager's own,
+        /// `Some("<name>")` = that agent's.
+        #[serde(default)]
+        agent: Option<String>,
     },
     /// Manager-flavour self-introspection. Same wire shape as
     /// `AgentRequest::Whoami`, but `role` is always `"manager"`.