core: fix krunkit virtiofs configuration

[jasonthird]

What changed

• Treat krunkit like VZ when generating Lima's default mount type.
• Keep explicit SSHFS aliases mapped to reverse-sshfs.
• Add platform-independent regression coverage for QEMU, VZ, and krunkit mount resolution.

Why

The CLI now converts krunkit's unsupported 9p mount type to virtiofs, but the Lima configuration generator still treated every non-VZ backend as QEMU and emitted 9p. As a result, starting krunkit failed Lima validation even when virtiofs was requested.

This change keeps the generated Lima configuration consistent with the CLI behavior added in #1609.

Impact

colima start --vm-type krunkit --mount-type virtiofs now generates a valid virtiofs Lima configuration. Existing QEMU, VZ, and SSHFS behavior is preserved.

Validation

• go test ./...
• gofmt
• git diff --check

LLM usage disclosure

OpenAI Codex using GPT-5.6-sol was used to investigate the root cause, implement the focused mount-type resolver change, and generate the regression tests. The resulting diff was inspected, formatted, and validated with the full Go test suite.

[Copilot]

Pull request overview

This PR fixes Lima config generation so krunkit uses a valid default mount type (virtiofs), matching the CLI’s mount-type normalization behavior and preventing Lima validation failures on krunkit.

Changes:

• Refactors mount-type selection into a helper (resolveMountType) and treats krunkit like VZ for default mount type resolution.
• Preserves mapping of SSH/SSHFS aliases to Lima’s reverse-sshfs.
• Adds regression tests for mount-type resolution across QEMU, VZ, and krunkit.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
environment/vm/lima/yaml.go	Uses a dedicated resolver for Lima mountType, defaulting krunkit to virtiofs (like VZ).
environment/vm/lima/yaml_test.go	Adds unit coverage for mount-type resolution behavior.

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[abiosoft]

Thanks :)

Kindly sign the DCO, you can check here for instructions.

[oanhnn]

@jasonthird
Please sign DCO by follow https://github.com/abiosoft/colima/pull/1610/checks?check_run_id=91642353654

It would be great if it were included in the next release.

[jasonthird]

@jasonthird Please sign DCO by follow https://github.com/abiosoft/colima/pull/1610/checks?check_run_id=91642353654

It would be great if it were included in the next release.

Thanks! I’ve signed off the commits and the DCO check is now passing.