ci: Lint Code flakes on golangci-lint jsonschema download timeout #977

Problem

The Lint Code job in CI - Build & Test intermittently fails before linting anything. golangci-lint validates .golangci.yml against a JSON schema that it downloads at run time, and the download times out:

[.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)

Seen on 2026-10-16 alone:

• run 38894294427 (fix(auth): keep API key permission constraints on create #957)
• run 38894924106 (sec(api): shell-escape the Bicep/ARM deploy script render (#958) #963)
• main's run at the time test(scheduler): kick the stale refresh with an unrestricted reader #960 was opened (its body notes the same failure)

Each one needed a manual re-run of the failed jobs. The lint itself reports 0 issues on these heads.

Impact

Every PR's required check fails at random. This costs a re-run, a CI cycle and a merge delay, and it trains people to dismiss red Lint runs.

Suggested fix

Stop depending on the network for config verification in CI. Pick one of:

• Set the golangci-lint action's verify: false and verify the config locally or in pre-commit instead.
• Vendor or cache the v2.10 schema.
• Run golangci-lint config verify as a separate, non-blocking step with a retry.

Keep the pinned lint version and the lint itself blocking.