Open existing agents from links and the CLI (#2324)

* feat(desktop): open existing agents from links

Register a stable agent deep link and route it through the existing Desktop window. Add a matching CLI command that resolves the local server and activates the requested agent without creating or messaging it.

* fix(desktop): recover agent link delivery

packages/desktop/src/desktop-startup.ts

@@ -1,5 +1,5 @@
 export interface DesktopStartupDependencies {
-  hasPendingOpenProjectPath: boolean;
+  hasPendingGuiLaunchRequest: boolean;
   runCliPassthroughIfRequested: () => Promise<boolean>;
   inheritLoginShellEnv: () => void;
   bootstrapGui: () => Promise<void>;
@@ -7,7 +7,7 @@ export interface DesktopStartupDependencies {
 }
 
 export async function runDesktopStartup(deps: DesktopStartupDependencies): Promise<void> {
-  if (!deps.hasPendingOpenProjectPath && (await deps.runCliPassthroughIfRequested())) {
+  if (!deps.hasPendingGuiLaunchRequest && (await deps.runCliPassthroughIfRequested())) {
     return;
   }