ci(lint): config verify fetches its schema over the network and flakes the lint gate #72

Summary

The CI "Lint Code" job runs golangci-lint config verify before golangci-lint run. config verify downloads its JSON schema from https://golangci-lint.run/jsonschema/golangci.v2.10.jsonschema.json at run time, so a slow or unreachable site fails the required lint gate even when the code is clean.

Observed on PR #71, a CLAUDE.md-only change, in run 38836492087:

[.golangci.yml] validate: compile schema: failing loading "https://golangci-lint.run/jsonschema/golangci.v2.10.jsonschema.json": ... context deadline exceeded (Client.Timeout exceeded while awaiting headers)
Process completed with exit code 3.

A re-run of the failed job is the only workaround today.

Options

1. Commit the v2.10 schema into the repo and point config verify at the local copy, if golangci-lint supports a schema override. Check this first.
2. Retry config verify a bounded number of times, and fail only if every attempt fails.
3. Drop config verify. golangci-lint run already rejects unknown or invalid config keys, so check how much verify adds beyond that.

Acceptance

• The lint gate no longer depends on golangci-lint.run being reachable, or it retries before failing.
• An invalid .golangci.yml still fails CI.