chore: exclude .mts sources from npm package

The compiled .mjs output in dist/ is what gets published.
Keep .d.mts declaration files for TypeScript consumers.

Author: oetr

.npmignore

@@ -26,8 +26,11 @@ example
 
 # Exclude all TypeScript source files
 *.ts
+*.mts
 !*.d.ts
+!*.d.mts
 *test*.d.ts
+*test*.d.mts
 
 
 # Exclude native fuzzer sources