Workstream: Engineering Excellence, Testing and Release

This issue tracks the overall effort to improve the engineering excellence, testing and release pipeline of the `gemini-cli` repository. The goal is to create a more robust, reliable, and contributor-friendly development and release process for both internal and external contributors.

This initiative is broken down into several key areas. Please see linked sub issues below.

This issue is part of a the larger GeminiCLI roadmap, work to detail it completely is still in flight.

## Relevant Files

### Release
- Main Release Code: [.github/workflows/release.yml](https://github.com/google-gemini/gemini-cli/blob/main/.github/workflows/release.yml)
- Main Release Action (logs & runs): https://github.com/google-gemini/gemini-cli/actions/workflows/release.yml
- Npm / Release docs: [docs/npm.mp](https://github.com/google-gemini/gemini-cli/blob/main/docs/npm.md)
- Current Docker Release: [.gcp/release-docker.yml](https://github.com/google-gemini/gemini-cli/blob/main/.gcp/release-docker.yml)

### Testing
- Integration test code: [integration-tests](https://github.com/google-gemini/gemini-cli/tree/main/integration-tests)
- Integration test Action: https://github.com/google-gemini/gemini-cli/actions/workflows/e2e.yml