fix(type-compiler): correct plugin export paths

[mojobeeping]

Summary

The published @deepkit/type-compiler@1.0.19 package exposes ./plugin, but the export map points at files that are not present in the tarball:

"./plugin": {
  "types": "./dist/cjs/plugin.d.ts",
  "require": "./dist/cjs/plugin.js",
  "default": "./dist/esm/plugin.js"
}

The published package contains the plugin files under dist/*/src/ instead:

dist/cjs/src/plugin.js
dist/cjs/src/plugin.d.ts
dist/esm/src/plugin.js
dist/esm/src/plugin.d.ts

This PR updates only the ./plugin export paths to match the files that are actually emitted.

Reproduction

rm -rf /tmp/mojobeep-deepkit-type-repro
mkdir -p /tmp/mojobeep-deepkit-type-repro
cd /tmp/mojobeep-deepkit-type-repro
npm init -y >/dev/null
npm install @deepkit/type-compiler@1.0.19 >/dev/null
node --input-type=module -e "import('@deepkit/type-compiler/plugin').catch(error => { console.log(error.code, error.message); process.exit(1) })"

Observed output:

ERR_MODULE_NOT_FOUND Cannot find module .../node_modules/@deepkit/type-compiler/dist/esm/plugin.js

Validation

I validated the corrected export paths against a clean install of the published package by patching only the local package metadata:

PATCHED_DEEPKIT_ESM_OK [ 'deepkitType' ] function
PATCHED_DEEPKIT_CJS_OK [ 'deepkitType' ] function
PATCHED_DEEPKIT_TYPES_OK

I also verified this repository change with:

node -e "const p=require('./packages/type-compiler/package.json'); console.log(JSON.stringify(p.exports['./plugin'], null, 2))"
git diff --check