feat(#1137): rich unread summary in loose ends and wake signal

- hive-sh4re: UnreadMatrix gains summary: String field (per-room breakdown)
- hive-matrix-mcp/protocol: add RoomUnread struct + UnreadSummary request
- hive-matrix-mcp/handlers: collect_unread() fetches per-room data;
  single-unread rooms include truncated last-message body + sender;
  multi-unread rooms carry count only
- hive-matrix-mcp/wake: format_unread_summary() builds wake body from
  RoomUnread slice; terse one-liner for single-room/single-message,
  bulleted list for multi-room; always appends read-hint
- hive-matrix-mcp/timeline: wake body now covers all rooms with unread
  at fire time, not just the triggering event; falls back to per-event
  teaser if notification counts haven't updated yet
- hive-ag3nt/mcp: matrix_unread_summary() replaces matrix_unread_rooms();
  UnreadMatrix loose end carries per-room summary lines; render shows
  room breakdown with sender: body for single-unread rooms

hive-ag3nt/src/bin/hive.rs

@@ -365,8 +365,15 @@ impl Surface for AgentSurface {
     }
 
     async fn wake_external(socket: &Path, from: String, body: String) -> Result<()> {
-        let resp: AgentResponse =
-            client::request(socket, &AgentRequest::Wake { from, body, transient: false }).await?;
+        let resp: AgentResponse = client::request(
+            socket,
+            &AgentRequest::Wake {
+                from,
+                body,
+                transient: false,
+            },
+        )
+        .await?;
         match resp {
             AgentResponse::Ok => Ok(()),
             AgentResponse::Err { message } => anyhow::bail!("wake: {message}"),
@@ -506,8 +513,15 @@ impl Surface for ManagerSurface {
     }
 
     async fn wake_external(socket: &Path, from: String, body: String) -> Result<()> {
-        let resp: ManagerResponse =
-            client::request(socket, &ManagerRequest::Wake { from, body, transient: false }).await?;
+        let resp: ManagerResponse = client::request(
+            socket,
+            &ManagerRequest::Wake {
+                from,
+                body,
+                transient: false,
+            },
+        )
+        .await?;
         match resp {
             ManagerResponse::Ok => Ok(()),
             ManagerResponse::Err { message } => anyhow::bail!("wake: {message}"),