Every provider now goes through the module-impl C ABI, so the LOGOS_METHOD
dispatch path is gone: parseProviderHeader, generateProviderDispatch,
ParsedMethod and the joinDocLines helper only it used (~300 lines), plus the
test that covered it.
`toQVariantConversion` is NOT removed — it is shared with live emitters — and
its test stays.
The flag is REFUSED rather than dropped. Without that, `--provider-header x.h`
falls through to the plugin-path branch, which reads the flag itself as a
plugin path and reports "Plugin file does not exist: --provider-header" — a
missing-file error for what is really a retired mode. It now exits 2 with a
message pointing at interface: "universal".
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
