Ess 0.4.1

Packaging fix for 0.4.0. The v0.4.0 release asset shipped without api/ess.json or api/natives.json
— the two manifests 0.4.0 was largely about. No framework code is affected; if you only installed
1_Ess.lua, 0.4.0 was fine and this changes nothing for you.

Fixed

• release.yml never ran build/manifest.py. ci.yml did, so CI went green while the published zip was
  missing the manifest: dist/ is gitignored, so ess.json doesn't exist in a fresh checkout, and
  package.py skipped it exactly as written. Added the generate step to the release workflow. This is a
  reminder that a passing CI job and a correct release artifact are different claims — the zip is now
  inspected, not assumed.
• build/package.py now WARNS LOUDLY when a manifest is missing instead of quietly shipping a zip without
  it. That silence is the only reason the 0.4.0 gap reached a published release.
• natives.json moved from gitignored dist/ to committed api/natives.json. It's captured from a
  live game by tools/dump_natives.py, so CI physically cannot regenerate it — a gitignored copy would
  have been absent from every release zip forever, no matter what the workflow did. It also changes
  essentially never (only if the game or bridge changes), which makes committing it the honest option. The
  two files now come from two different places on purpose: dist/ess.json is derived from src/ and so is
  regenerated every build to guarantee it's never stale; api/natives.json is captured from outside this
  repo and so is committed. Both are documented that way at every reference.