[backport rh-test] Fix cloud routing issues caused by incorrect api_base calculation (#6578)

Backport of #6572 to `rh-test`

Automatically created by backport workflow.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6578-backport-rh-test-Fix-cloud-routing-issues-caused-by-incorrect-api_base-calculation-2a16d73d36508157a3edfca38af1cf03)
by [Unito](https://www.unito.io)

Co-authored-by: Jin Yi <[email protected]>

Author: comfy-pr-bot

src/scripts/api.ts

@@ -382,7 +382,13 @@ export class ComfyApi extends EventTarget {
     super()
     this.user = ''
     this.api_host = location.host
-    this.api_base = location.pathname.split('/').slice(0, -1).join('/')
+    const pathname = location.pathname
+    const isCloudSpaRoute = isCloud && pathname.startsWith('/cloud/')
+    if (isCloudSpaRoute) {
+      this.api_base = ''
+    } else {
+      this.api_base = pathname.split('/').slice(0, -1).join('/')
+    }
     console.log('Running on', this.api_host)
     this.initialClientId = sessionStorage.getItem('clientId')
   }