Add doctor command for environment checks

[baily-zhang]

Motivation

Users need a read-only way to diagnose config, Docker, auth, and emulator connectivity from the CLI.

Changes

• add a new lstk doctor command with read-only config, Docker, auth, and emulator checks
• add timeout handling, per-check limits, concurrent emulator checks, and TUI support
• add unit and integration coverage for doctor success, warning, and failure scenarios

Tests

• go test ./cmd/... ./internal/...
• cd test/integration && LSTK_KEYRING=file go test -count=1 -run TestDoctor ./...

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[gtsiolis]

Thanks for contributing, @baily-zhang! ❤️

The doctor command looks like a good first iteration.

Heads-up: The team is sorting out a contribution policy process for this repository, we will follow up here as soon as we have clarity on next steps. Thanks for your patience. ⏳

[baily-zhang]

Thanks for the update, and no worries. Glad to hear the first iteration looks useful. Happy to wait, and I’m available to make follow-up changes if needed once the process is in place.

[baily-zhang]

Btw, here's what it looks like in different scenarios

[gtsiolis]

Thanks for your patience, @baily-zhang! ❤️

Closing this as the team decided to restrict code contributions from outside collaborators in #454.

From README.md:

You can read the source, build it, and fork it freely — but we don't accept pull requests from outside collaborators.

The best way to participate is to open a well-formed issue. A bug report we can reproduce is worth more to us than a patch, because it captures the part we can't discover ourselves

From CONTRIBUTING.md:

[...] Why we don't accept outside pull requests

lstk's architecture and roadmap move quickly, and reviewing outside patches requires context and coordination we cannot currently offer fairly. An issue lets us validate the problem and decide on an approach before anyone spends time implementing it.

On this PR specifically, we're working on a doctor command that will be released soon. 🙏