feat(frontend): surfaces live web (workstate live, background, inbox, reconnect) (#13)

Lot F5 du chantier server/client mode : le client web consomme les frames
event.domain (B7) pour animer ses surfaces live.

- webLive.ts : consommation du flux event.domain (workstate, background,
  inbox).
- useLiveReconnect.ts : reconnexion du flux live.
- wsLiveClient.ts / index.ts : câblage du transport live.
- WebWorkspace.tsx : surfaces live branchées.
- Tests : WebWorkspaceLive.test.tsx, wsLiveClientReconnect.test.ts,
  WebApp.test.tsx.

Validé : frontend 753 tests verts, desktop non régressé.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/adapters/http/wsLiveClient.ts

@@ -263,15 +263,19 @@ export class WsLiveClient {
       this.setConnState("closed");
       return;
     }
-    // Only reconnect when there is a live terminal to re-attach; otherwise stay
-    // idle until the next explicit use.
+    this.setConnState("reconnecting");
+    // Reconnect while anything still needs the socket: a live terminal to
+    // re-attach (F3) OR an active domain-event subscription (F5 live surfaces).
+    // Otherwise stay idle until the next explicit use.
     if (this.terminals.size > 0) {
-      this.setConnState("reconnecting");
       for (const sub of this.terminals.values()) sub.onData(notice("déconnecté — reconnexion…"));
-      this.scheduleReconnect();
-    } else {
-      this.setConnState("reconnecting");
     }
+    if (this.needsReconnect()) this.scheduleReconnect();
+  }
+
+  /** Whether the socket should auto-reconnect (a terminal or a live subscription). */
+  private needsReconnect(): boolean {
+    return this.terminals.size > 0 || this.domainEventHandler !== null;
   }
 
   private scheduleReconnect(): void {
@@ -293,8 +297,8 @@ export class WsLiveClient {
       await this.connect();
       await this.reattachAll();
     } catch {
-      // Still down: back off and retry (unless everything was detached/closed).
-      if (this.terminals.size > 0) this.scheduleReconnect();
+      // Still down: back off and retry (unless nothing needs the socket anymore).
+      if (this.needsReconnect()) this.scheduleReconnect();
     }
   }