fix: point package types at dist where the build emits them

[imharjot]

The package publishes dist/, but its declaration paths point to the unpublished root index.d.ts. Point the top-level types field to dist/index.d.ts and select the matching emitted declarations for ESM (index.d.mts) and CommonJS (index.d.ts).

Added a test that builds and installs the actual tarball, checks that its advertised declaration files exist, then compiles and runs ESM and CommonJS consumers. The original manifest fails the missing-file check.

Validation: npm test passed (50 tests); the new test passes targeted ESLint. Repository-wide ESLint still reports existing errors in the unchanged source and configuration.

Closes #37

[imharjot]

Rebased onto current master and added a test against the installed tarball rather than only the source tree. It catches the missing advertised declaration on the original manifest, then compiles and runs both ESM and CommonJS consumers with the fix. All 50 tests pass locally. The new test passes ESLint; the repository-wide lint command still reports errors in unchanged files.

[imharjot]

The refreshed workflow run is marked action_required and has not started any check jobs. Could a maintainer approve or unblock it? The local test results are recorded above.