chore: reproducible pipeline with dev containers (#10305)

# Which Problems Are Solved

- The previous monorepo in monorepo structure for the login app and its
related packages was fragmented, complicated and buggy.
- The process for building and testing the login container was
inconsistent between local development and CI.
- Lack of clear documentation as well as easy and reliable ways for
non-frontend developers to reproduce and fix failing PR checks locally.

# How the Problems Are Solved

- Consolidated the login app and its related npm packages by moving the
main package to `apps/login/apps/login` and merging
`apps/login/packages/integration` and `apps/login/packages/acceptance`
into the main `apps/login` package.
- Migrated from Docker Compose-based test setups to dev container-based
setups, adding support for multiple dev container configurations:
  - `.devcontainer/base`
  - `.devcontainer/turbo-lint-unit`
  - `.devcontainer/turbo-lint-unit-debug`
  - `.devcontainer/login-integration`
  - `.devcontainer/login-integration-debug`
- Added npm scripts to run the new dev container setups, enabling exact
reproduction of GitHub PR checks locally, and updated the pipeline to
use these containers.
- Cleaned up Dockerfiles and docker-bake.hcl files to only build the
production image for the login app.
- Cleaned up compose files to focus on dev environments in dev
containers.
- Updated `CONTRIBUTING.md` with guidance on running and debugging PR
checks locally using the new dev container approach.
- Introduced separate Dockerfiles for the login app to distinguish
between using published client packages and building clients from local
protos.
- Ensured the login container is always built in the pipeline for use in
integration and acceptance tests.
- Updated Makefile and GitHub Actions workflows to use
`--frozen-lockfile` for installing pnpm packages, ensuring reproducible
installs.
- Disabled GitHub release creation by the changeset action.
- Refactored the `/build` directory structure for clarity and
maintainability.
- Added a `clean` command to `docks/package.json`.
- Experimentally added `knip` to the `zitadel-client` package for
improved linting of dependencies and exports.

# Additional Changes

- Fixed Makefile commands for consistency and reliability.
- Improved the structure and clarity of the `/build` directory to
support seamless integration of the login build.
- Enhanced documentation and developer experience for running and
debugging CI checks locally.

# Additional Context

- See updated `CONTRIBUTING.md` for new local development and debugging
instructions.
- These changes are a prerequisite for further improvements to the CI
pipeline and local development workflow.
- Closes #10276

packages/.changeset/README.md

@@ -0,0 +1,8 @@
+# Changesets
+
+Hello and welcome! This folder has been automatically generated by `@changesets/cli`, a build tool that works
+with multi-package repos, or single-package repos to help you version and publish your code. You can
+find the full documentation for it [in our repository](https://github.com/changesets/changesets)
+
+We have a quick list of common questions to get you started engaging with this project in
+[our documentation](https://github.com/changesets/changesets/blob/main/docs/common-questions.md)