feat: display per-agent model override in agent monitor tree

Parse the model field from Agent/Task tool input and surface it in the
agent monitor panel as a purple subtitle, so users can immediately see
which agents are running on a non-default model.

Closes #207

src-tauri/src/types.rs

@@ -292,6 +292,8 @@ pub struct AgentStartEvent {
     pub conversation_id: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub parent_tool_use_id: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub model: Option<String>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]

src-tauri/src/wsl_bridge.rs

@@ -1301,14 +1301,19 @@ fn process_json_line(
                                 .and_then(|v| v.as_str())
                                 .unwrap_or("unknown")
                                 .to_string();
+                            let model = input
+                                .get("model")
+                                .and_then(|v| v.as_str())
+                                .filter(|s| !s.is_empty())
+                                .map(|s| s.to_string());
                             let now = SystemTime::now()
                                 .duration_since(UNIX_EPOCH)
                                 .unwrap_or_default()
                                 .as_millis() as u64;
 
                             tracing::debug!(
-                                "Emitting agent-start: id={}, desc={}, type={}, parent={:?}",
-                                id, description, subagent_type, parent_tool_use_id
+                                "Emitting agent-start: id={}, desc={}, type={}, model={:?}, parent={:?}",
+                                id, description, subagent_type, model, parent_tool_use_id
                             );
 
                             let _ = app.emit(
@@ -1318,6 +1323,7 @@ fn process_json_line(
                                     agent_id: None, // Will be updated when SubagentStart hook is received
                                     description,
                                     subagent_type,
+                                    model,
                                     started_at: now,
                                     conversation_id: conversation_id.clone(),
                                     parent_tool_use_id: parent_tool_use_id.clone(),