Export solid plugin properly

[ericc-ch]

Define the export properly for solid plugin in package.json, so instead of

import solidPlugin from "./node_modules/@opentui/solid/scripts/solid-plugin"

await Bun.build({
  entrypoints: ["./index.tsx"],
  target: "bun",
  outdir: "./build",
  plugins: [solidPlugin],
  compile: {
    target: "bun-darwin-arm64",
    outfile: "app-macos",
  },
})

We can do

import solidPlugin from "@opentui/solid/plugin"
// or
import solidPlugin from "@opentui/solid/bun-plugin"

await Bun.build({
  entrypoints: ["./index.tsx"],
  target: "bun",
  outdir: "./build",
  plugins: [solidPlugin],
  compile: {
    target: "bun-darwin-arm64",
    outfile: "app-macos",
  },
})

Would be a nice qol improvement

Is there anything that prevents this? I'm genuinely curious because it seems easy I'll try it and if it is then I'll open a PR later :)