fix(cloudflare): Json() bindings deploy as native types instead of strings

[sam-goodwin]

Closes #1450

Problem

Json(value) bindings behaved differently between local dev and production:

• Local dev: miniflare received the raw value, so env.IS_DEVELOPMENT was a native boolean.
• Production: prepareWorkerMetadata called JSON.stringify(binding.json) before sending the binding to the Cloudflare API, so the runtime injected the JSON string ("false") instead of the native value (false). Since Boolean("false") === true, this silently broke conditional checks in production.

Fix

Send the raw value in the json field of the worker metadata binding, exactly as wrangler does (wrangler converts non-string vars to { type: "json", name, json: value } with the raw parsed value — see create-worker-upload-form.ts). The whole metadata object is JSON.stringify-ed once when appended to the upload form, so the value serializes correctly without double encoding.

Also updated WorkerBindingJson.json from string to unknown to match.

Usage

import { Worker, Json } from "alchemy/cloudflare";

const worker = await Worker("api", {
  entrypoint: "./src/worker.ts",
  bindings: {
    IS_DEVELOPMENT: Json(false),
    MAX_RETRIES: Json(3),
    FEATURES: Json({ beta: true }),
  },
});

// src/worker.ts — now identical in local dev and production:
export default {
  async fetch(request, env) {
    console.log(typeof env.IS_DEVELOPMENT, env.IS_DEVELOPMENT); // "boolean" false
    if (env.IS_DEVELOPMENT) {
      // no longer incorrectly taken in production
    }
    return new Response("ok");
  },
};

Test

Added "json bindings are injected as native types" to worker.test.ts: deploys a worker with boolean, number, and object Json bindings and asserts the deployed worker observes the native types (typeof env.IS_DEV === "boolean", etc.) via its workers.dev URL.

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commit: 487e773