[Code Quality] Add CI enforcement for appendoneelement, timenowsub, and stringsjoinone linters #48057

Description

Three custom linters have been verified as production-clean and enforcement-ready but are not yet enabled in CI:

• appendoneelement — rewrites append(s, []T{x}...) to append(s, x). Zero production violations, type-gated correctly.
• timenowsub — rewrites time.Now().Sub(t) to time.Since(t). Zero production violations, uses safe type resolution.
• stringsjoinone — simplifies single-element strings.Join. Zero production violations, golden-verified.

All three are clean (zero violations in default and js/wasm), autofix-capable with RunWithSuggestedFixes, nolint+filecheck-wired, and golden-test verified.

Suggested Changes

• Add all three linters to the enforced set in .github/workflows/cgo.yml (around lines 1227/1230)
• Verify make golint-custom passes with the new enforcement

Files Affected

• .github/workflows/cgo.yml (enforcement list ~line 1227)
• pkg/linters/registry.go

Success Criteria

• All three linters listed in the CI-enforced set in cgo.yml
• make golint-custom passes cleanly
• CI enforces these checks on new PRs

Source

Extracted from [sergo] Sergo Report - 2026-07-25

Priority

Medium — Low-risk quality guard; linters already verified production-clean.

🔍 Task mining by Discussion Task Miner - Code Quality Improvement Agent · sonnet46 · 47 AIC · ⌖ 5.49 AIC · ⊞ 7.2K · ◷

• expires on Jul 26, 2026, 11:12 AM UTC-08:00