feat: align task pipe protocol and hmac

src/pipe/protocol.rs

@@ -12,6 +12,9 @@ pub enum BrowserMessage {
         #[serde(default)]
         capabilities: Vec<String>,
     },
+    SubmitTask {
+        instruction: String,
+    },
     Response {
         seq: u64,
         success: bool,
@@ -31,6 +34,14 @@ pub enum AgentMessage {
         agent_id: String,
         supported_actions: Vec<Action>,
     },
+    LogEntry {
+        level: String,
+        message: String,
+    },
+    TaskComplete {
+        success: bool,
+        summary: String,
+    },
     Command {
         seq: u64,
         action: Action,