chore(login): migrate nextjs login to monorepo (#10134)

# Which Problems Are Solved

We move the login code to the zitadel repo.

# How the Problems Are Solved

The login repo is added to ./login as a git subtree pulled from the
dockerize-ci branch.
Apart from the login code, this PR contains the changes from #10116

# Additional Context

- Closes https://github.com/zitadel/typescript/issues/474
- Also merges #10116  
- Merging is blocked by failing check because of:
- https://github.com/zitadel/zitadel/pull/10134#issuecomment-3012086106

---------

Co-authored-by: Max Peintner <peintnerm@gmail.com>
Co-authored-by: Max Peintner <max@caos.ch>
Co-authored-by: Florian Forster <florian@zitadel.com>

docker-bake.hcl

@@ -0,0 +1,5 @@
+target "typescript-proto-client" {
+  contexts = {
+    proto-files = "target:proto-files"
+  }
+}