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>

dockerfiles/proto-files.Dockerfile

@@ -0,0 +1,8 @@
+FROM bufbuild/buf:1.54.0 AS proto-files
+RUN buf export https://github.com/envoyproxy/protoc-gen-validate.git --path validate --output /proto-files && \
+    buf export https://github.com/grpc-ecosystem/grpc-gateway.git --path protoc-gen-openapiv2 --output /proto-files && \
+    buf export https://github.com/googleapis/googleapis.git --path google/api/annotations.proto --path google/api/http.proto --path google/api/field_behavior.proto --output /proto-files
+
+FROM scratch
+COPY --from=proto-files /proto-files /
+COPY ./proto /