fix: resolve plugin host root from published dist layout

[KehaoC]

Summary

Fixes plugin host package linking for published builds by resolving the real @jackwener/opencli package root from the running module path instead of assuming it is always one directory up.

In published installs, src/plugin.ts compiles under dist/src/plugin.js, so the old dirname + '..' logic could point plugin node_modules/@jackwener/opencli at dist/ instead of the package root. That breaks package export resolution for imports like @jackwener/opencli/registry.

Changes

• Add resolveHostOpencliRoot() to walk upward until it finds the host package package.json.
• Use that helper for plugin host symlinking and esbuild binary lookup.
• Add a regression test for resolving from a compiled dist/src/plugin.js layout.

Validation

• npm test -- --run src/plugin.test.ts
• npm run typecheck

Fixes #843
Refs #722