fix(config): accept string values for k9s.gpuVendors in the schema - #4298

k9s.gpuVendors is a map[string]string in internal/config/k9s.go
(vendor name -> resource name, e.g. bozo: bozo/gpu), and that is how the
README documents it. The JSON schema (internal/config/json/schemas/k9s.json)
requires every value to be an object with vendor and model, so a config
that follows the README fails validation and k9s logs
k9s config file ... load failed, while a config that follows the schema would
not unmarshal into the Go type. The mismatch has been there since the setting
was added in v0.50.8.

Changes:

• schema: gpuVendors values are strings;
• testdata/k9s/cool.yaml: add a gpuVendors entry so TestValidateK9s/happy
  covers it;
• README config sample: replace three tab-indented comment lines with spaces
  (the tabs make the sample invalid YAML when copied), and remove a stale
  top-level k9s.noIcons line (the setting lives under k9s.ui.noIcons, which
  the sample already shows; the top-level key is not in the schema or the
  K9s struct).

Testing: I did not run go test (the module cache here lacks gojsonschema).
I checked the README sample and testdata/k9s/cool.yaml against the schema
with a small script implementing the draft-07 keywords the schema uses: with
the old schema gpuVendors.bozo fails with "expected object, got string";
with the new schema both files validate.

This PR was written in part with the assistance of generative AI.
This change was drafted with AI assistance and reviewed by me.

🤖 Generated with Claude Code