fix(cli): respect gateway name for mTLS lookup

[alexclewontin]

Summary

Fix CLI mTLS certificate discovery so an explicit gateway name is honored for loopback HTTPS endpoints. This unblocks the Kubernetes setup flow where the Helm-generated client bundle is installed under gateways/k8s/mtls and the gateway is registered as --name k8s, as suggested here: https://docs.nvidia.com/openshell/kubernetes/setup.

Inferring openshell as the default gateway name when no --name is provided still occurs (crates/openshell-cli/src/run.rs:911-927)

Related Issue

None.

Changes

• Removed endpoint-based loopback canonicalization from the mTLS cert preflight lookup; the helper now checks the already-selected gateway name.
• Added regression coverage for direct mTLS bundle lookup by explicit gateway name.
• Added integration coverage for gateway registration across the relevant loopback naming cases:
  • explicit --name k8s uses gateways/k8s/mtls
  • omitted --name on loopback derives and uses gateways/openshell/mtls
  • explicit --name k8s does not fall back to gateways/openshell/mtls

Testing

• Built and ran the fixed CLI against the local Kubernetes gateway: cargo run -p openshell-cli -- gateway add https://127.0.0.1:8080 --local --name k8s
• Verified the registered gateway connects: cargo run -p openshell-cli -- status
• cargo test -p openshell-cli --test mtls_integration gateway_add_mtls_loopback passes
• cargo test -p openshell-cli --test mtls_integration passes
• cargo test -p openshell-cli mtls_certs_exist_for_gateway_uses_explicit_name_for_loopback_endpoint passes
• mise run pre-commit passes

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)

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[maxamillion]

/ok to test 9b077ff

[maxamillion]

@alexclewontin this looks good, if you can rebase on main and fix the conflict I'll gladly merge

[alexclewontin]

@maxamillion thanks, rebased & conflicts fixed

[maxamillion]

/ok to test 9d56ba5