ci: run all jobs unconditionally, remove change detection (#2947)
* ci: run all jobs unconditionally, remove change detection
CI was skipping jobs based on which files changed -- including on pushes
to main. A Rust-only commit would skip Go tests, Python lint, etc. This
means regressions from cross-language interactions go undetected and main
isn't a reliable known-good baseline.
Remove the change detection job entirely. Every CI job now runs on every
trigger (push, PR, merge group). The setup job remains as a minimal shim
to pass SUPPORTED_PYTHONS to matrix jobs (env context isn't available in
strategy.matrix).
Also fixes two pre-existing bugs in the ci-complete gate: version-check,
build-cog, and fuzz-go results were never checked, so failures in those
jobs were silently ignored.
* fix: resolve lint errors in test-harness caught by running Go lint unconditionally
errcheck violations (unchecked error returns on Cleanup, RemoveAll,
Close, Cmd.Run) and gocritic octal literal style (0644 -> 0o644).
These were introduced in #2942 and went undetected because CI skipped
Go lint when only Go files in tools/ changed.
* fix: resolve remaining lint errors in test-harness
More gocritic (octal literals, if-else chains), gosec (SSRF false
positives on hardcoded GitHub/PyPI URLs), modernize (maps.Copy,
strings.SplitSeq, built-in min), and misspell fixes.
