fix(ci): add golangci-lint step and PKGBUILD build flags
Add golangci-lint-action to CI workflow (Linux x64 only) after
the Test step. Update PKGBUILD build command to include -trimpath
and -ldflags=-s flags matching the CI build step.
Resolves COMP #18 (linter in CI) and COMP #19 (PKGBUILD flags).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>