PR based on https://github.com/clawshell/clawshell/pull/73

[xichen1997]

This PR is based on #73

Original info:

1. support oauth login
2. support OpenAI Codex login
3. support Google Antigravity oauth login, but because of the git security policy I cannot upload the oauth secret here, also need to set env var CLAWSHELL_ONBOARD_SHOW_ANTIGRAVITY_OAUTH=true to show it
4. add Docker support and docker compose support, so developer can verify and test more easier
The new architecture and flow docs in the docs folder

Current progress: I have cleaned all the code for google/antigravity Oauth, which won't be supported in the future, and now it can build with:

podman run --rm -v $(pwd):/workspace -w /workspace rust:latest sh -c "cargo build && cargo test"

However, the podman compose up will give several configuration warnings or errors:

openclaw-gateway  | 2026-03-19T22:15:12.186+00:00 Missing config. Run `openclaw setup` or set gateway.mode=local (or pass --allow-unconfigured).
openclaw-gateway  | 2026-03-19T22:15:12.186+00:00 Missing config. Run `openclaw setup` or set gateway.mode=local (or pass --allow-unconfigured).
openclaw-gateway  | 2026-03-19T22:15:12.186+00:00 Missing config. Run `openclaw setup` or set gateway.mode=local (or pass --allow-unconfigured).
openclaw-gateway  | 2026-03-19T22:15:12.186+00:00 Missing config. Run `openclaw setup` or set gateway.mode=local (or pass --allow-unconfigured).
openclaw-gateway  | 2026-03-19T22:15:12.186+00:00 Missing config. Run `openclaw setup` or set gateway.mode=local (or pass --allow-unconfigured).
openclaw-gateway  | 2026-03-19T22:15:12.186+00:00 Missing config. Run `openclaw setup` or set gateway.mode=local (or pass --allow-unconfigured).
openclaw-gateway exited with code 1 (restarting)

[xichen1997]

As per @ADD-SP's comment, the official way to configure Docker for OpenClaw is documented here: https://docs.openclaw.ai/install/docker.

I recommend we keep the Docker setup for clawshell only rather than both.

[xichen1997]

I have deleted the docker part temporarily since we have to include openclaw image for running the openclaw CLI, which is way to heavy for a proxy tool like clawshell.

Keep the oauth for codex part and tested it could work on my Mac mini with vanilla OpenClaw.

[ADD-SP]

Could you squash all commit into a single commit, the author is https://github.com/u20024804, and you are the co-author, so that I can rebase and merge this PR.

[ADD-SP]

Force pushed 75fbaa8 to fix incorrect commit message.