`vp migrate` silently drops custom lint rules when a `jsPlugin`'s namespace can't be derived

[TheAlexLichter]

Describe the bug

When vp migrate merges .oxlintrc.json into vite.config.ts, it drops all rules whose namespace it can't match to a plugin.

For a local jsPlugin like ./lint/kumo.js, the plugin's real namespace (kumo, from its meta.name) is never derived from the path, so every kumo/* rule is removed from the merged config.

This happens silently for rules while dropped plugins produce a warning.

Solution approach

We could resolve the real namespace (import the plugin and read meta.name) which is exactly what oxlint does at lint time.

Reproduction

cloudflare/kumo@2a463f7

Steps to reproduce

1. Try migrating this app via vp migrate
2. See the rules missing

System Info

Source        .node-version
  Source Path   /Users/alichter/Programming/kumo/.node-version
  Project Root  /Users/alichter/Programming/kumo

Tool Paths:
  node  /Users/alichter/.vite-plus/js_runtime/node/24.12.0/bin/node
  npm   /Users/alichter/.vite-plus/js_runtime/node/24.12.0/bin/npm
  npx   /Users/alichter/.vite-plus/js_runtime/node/24.12.0/bin/npx

Package Manager:
  Name          pnpm
  Version       10.22.0
  Source        packageManager
  Source Path   /Users/alichter/Programming/kumo/package.json
  Project Root  /Users/alichter/Programming/kumo
  Bin Path      /Users/alichter/.vite-plus/package_manager/pnpm/10.22.0/pnpm/bin/pnpm

Used Package Manager

pnpm

Logs

Validations

• Read the Contributing Guidelines.
• Check that there isn't already an issue for the same bug.
• Confirm this is a Vite+ issue and not an upstream issue (Vite, Vitest, tsdown, Rolldown, or Oxc).
• The provided reproduction is a minimal reproducible example.