docs: prepare for archiving the TypeScript repo (#10751)

# Which Problems Are Solved

The Login mirror repo https://github.com/zitadel/typescript is outdated.
With the DevX improvements done in #10571, forking the zitadel repo and
developing and deploying the Login became easy. This means, the
maintenance and mental overhead of syncing to the mirror repo is not
justified anymore.
This PR removes all references and mentions of the mirror repo, so we
can archive it.

# How the Problems Are Solved

- Fixed the *Deploy with Vercel* button to source the Login app from the
https://github.com/zitadel/zitadel repo.
- Renamed *Typescript Login UI* to *Login app*. This reflects the Nx
terminology in the Zitadel repo, as the Login is an Nx project in the
`apps` directory.
- Changed the typescript-repo route and configured a Vercel redirect
from `/docs/guides/integrate/login-ui/typescript-repo` to
`/docs/guides/integrate/login-ui/login-app`

# Additional Changes

- Removes the *Beta* status from the Login application

# Additional Context

- Depends on #10571 because it contains links to the updated
CONTRIBUTING.md as well as the updated docs build command in Vercel.json

---------

Co-authored-by: Copilot <[email protected]>

docs/vercel.json

@@ -221,6 +221,11 @@
       "destination": "/docs/guides/integrate/login/hosted-login#password-reset",
       "permanent": true
     },
+    {
+      "source": "/docs/guides/integrate/login-ui/typescript-repo",
+      "destination": "/docs/guides/integrate/login-ui/login-app",
+      "permanent": true
+    },
     {
       "source": "/docs/legal/service-description/billing",
       "destination": "https://help.zitadel.com/pricing-and-billing-of-zitadel-services",