Fix notifications opening the wrong workspace (#2331)

* fix(app): open notifications on the right host

Agent notifications previously omitted workspace ownership, so a cold target host was treated as missing and fell back to its empty home route. Carry the authoritative workspace and keep older notifications on a target-host resolver until lookup is conclusive.

* fix(app): separate notification and agent URL routing

Notifications use their authoritative workspace target directly. Stable agent URLs remain server-and-agent targets whose workspace is resolved by the agent route.

* fix(protocol): preserve notification workspace targets

Both attention message variants retain workspaceId through outbound validation so notification clicks receive the authoritative route target.

* test(app): use workspace-scoped notification target

* test(server): give notification agents workspace targets

* test(app): target notification workspace in navigation e2e

packages/app/src/utils/host-routes.ts

@@ -1,4 +1,5 @@
 import { Buffer } from "buffer";
+import { buildAgentDeepLinkRoute } from "@getpaseo/protocol/agent-deep-link";
 
 type NullableString = string | null | undefined;
 const BASE64_WORKSPACE_ID_PREFIX = "b64_";
@@ -389,7 +390,10 @@ export function buildHostAgentDetailRoute(serverId: string, agentId: string, wor
   if (!normalizedServerId || !normalizedAgentId) {
     return "/" as const;
   }
-  return `${buildHostRootRoute(normalizedServerId)}/agent/${encodeSegment(normalizedAgentId)}` as const;
+  return buildAgentDeepLinkRoute({
+    serverId: normalizedServerId,
+    agentId: normalizedAgentId,
+  });
 }
 
 export function buildHostRootRoute(serverId: string) {