refactor(server): normalize compute driver config acquisition

[elezar]

Summary

Normalize compute driver config acquisition so the CLI prepares gateway startup state while the server constructs only the selected driver config at runtime.

Related Issue

Closes #1949

Changes

• Normalize compute driver config type imports and driver service aliases.
• Move Docker/VM/Podman/Kubernetes config construction into selected-driver runtime setup.
• Carry guest TLS defaults through ServerStartupConfig and apply them to selected local driver config.
• Preserve config files for K8s ServiceAccount bootstrap and selected driver table parsing.
• Add tests for ignoring unselected invalid driver tables and reporting selected invalid driver tables.

Testing

• mise run pre-commit passes
• Unit tests added/updated
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)

[elezar]

gator-agent

PR Review Status

Validation: this maintainer-authored PR is project-valid because it is concentrated server compute-driver configuration work linked to #1949. It narrows startup validation to the selected driver while preserving local driver runtime defaults.
Head SHA: e3f5996f5443b552b4c8f48827f2254899aab1f7

Review findings:

• No blocking findings remain.
• Nonblocking warning from the independent review: crates/openshell-server/src/lib.rs changes run_server and the new ServerStartupConfig to crate-private. If openshell-server is intended as a consumable library API, keep a public entrypoint or document the API removal.
• Nonblocking suggestion: add focused coverage for guest TLS default propagation through ServerStartupConfig into a selected local driver.

Docs: no Fern docs update is required; this is an internal startup/config acquisition refactor with no direct user-facing UX change.
E2E: I applied test:e2e because the change affects gateway compute-driver runtime setup.
Checks: DCO and Helm Lint are passing. OpenShell / Branch Checks is still pending for this head, and the required E2E gate needs to run after the label change.

Next state: gator:watch-pipeline

[github-actions]

Label test:e2e applied for e3f5996. Open the existing run and click Re-run all jobs to execute with the label set. The run will execute the standard E2E suite after building the required gateway and supervisor images once. The matching required CI gate status on this PR will flip green automatically once the run finishes.

[elezar]

gator-agent

Maintainer Approval Needed

Gator validation and PR monitoring are complete.

Validation: maintainer-authored, project-valid server compute-driver configuration refactor linked to #1949.
Review: no blocking findings remain. Prior independent-review notes were nonblocking.
Docs: no Fern docs update required; this is an internal startup/config acquisition refactor with no direct user-facing UX change.
Checks: OpenShell / Branch Checks, OpenShell / Helm Lint, DCO, and required CI gate statuses are passing for head e3f5996f5443b552b4c8f48827f2254899aab1f7.
E2E: test:e2e is applied and OpenShell / E2E is passing. GPU E2E is not required for this PR.

Human maintainer approval or merge decision is now required.