feat: implement websocket-stream for journal server

Integrate `websocket-stream` to handle MQTT broker upgrades in the
CLI and add granular connection status tracking to the UI.

- Add `websocket-stream` dependency
- Update CLI to use `websocket-stream` for socket upgrades
- Enhance `journalStream` store with `connectionStatus` and
  `connectionError` states
- Add visual connection status indicators to `App` and `JournalPanel`

src/components/journal/JournalPanel.tsx

@@ -38,12 +38,17 @@ export const JournalPanel: Component<JournalPanelProps> = (props) => {
         <div class="flex items-center justify-between px-3 py-2 border-b border-gray-200">
           <div class="flex items-center gap-2">
             <h2 class="text-sm font-semibold text-gray-700">Journal</h2>
-            <Show when={stream.connected}>
-              <span
-                class="w-2 h-2 rounded-full bg-green-500"
-                title="Connected"
-              />
-            </Show>
+            <span
+              class="w-2 h-2 rounded-full"
+              classList={{
+                "bg-gray-400": stream.connectionStatus === "disconnected",
+                "bg-yellow-400 animate-pulse":
+                  stream.connectionStatus === "connecting",
+                "bg-green-500": stream.connectionStatus === "connected",
+                "bg-red-500": stream.connectionStatus === "error",
+              }}
+              title={stream.connectionStatus}
+            />
           </div>
           <button
             onClick={props.onClose}
@@ -104,7 +109,10 @@ const ConnectDialog: Component = () => {
       await hydrateFromServer(sessionId);
       await connectStream(sessionId, brokerUrl);
     } catch (e) {
-      setError(e instanceof Error ? e.message : "Connection failed");
+      const msg = e instanceof Error ? e.message : "Connection failed";
+      setError(msg);
+      // If connectStream threw, the error handler also sets connectionStatus to error.
+      // Make sure the error message is captured.
     } finally {
       setConnecting(false);
     }