Set up your x402 endpoint

I'm trying to get my x402 endpoint indexed in the CDP Bazaar discovery, but the Seller Tools Validator (https://agentic.market/validate) shows it has issues that need fixing. Help me update my code.

## What x402 + the Bazaar are
x402 v2 is an HTTP payment protocol where paid endpoints respond with `HTTP 402 Payment Required` plus a base64-encoded `payment-required` **header** carrying a JSON envelope: `{ x402Version: 2, accepts: [...], resource: {...}, extensions: {...} }`. (On v1 the same envelope was carried in the response **body** instead.) The CDP Bazaar is a discovery index that catalogs endpoints whose 402 responses include a properly-shaped `extensions.bazaar` object. An endpoint only gets cataloged after the CDP facilitator processes its first verify+settle. When the Bazaar probes a candidate resource it now uses the example request declared under `extensions.bazaar.info.input` (falling back to an empty request if none is provided), so servers can enforce request validation before payment validation without failing the probe — make sure your `info.input` example is representative.

Full spec: https://agentic.market/validate — please reference the **"Quickstart for Sellers"** section, which shows the exact `bazaarResourceServerExtension` registration + `declareDiscoveryExtension()` helper usage for Node.js / Go / Python.

## My endpoint
URL: GET https://api.example.com/
Stack: Node.js (Express, Fastify, etc.)

## What the corrected 402 response should look like
After your fix, the decoded `payment-required` envelope should match this shape (with my actual values, shown below):
```json
{
  "x402Version": 2,
  "error": "Payment required",
  "resource": {
    "url": "https://api.example.com/",
    "mimeType": "application/json"
  },
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "amount": "1000",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "payTo": "<your merchant wallet address>",
      "maxTimeoutSeconds": 300
    }
  ],
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": "<example response>"
        }
      },
      "schema": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "type": "object"
      }
    }
  }
}
```

## Please update my code to:
1. Make sure I'm using the **CDP facilitator** at `https://api.cdp.coinbase.com/platform/v2/x402/facilitator` (not `x402.org`) — only CDP-settled endpoints get cataloged in the CDP Bazaar.
2. Install/import `@x402/extensions/bazaar` (or the equivalent for my stack) and **register `bazaarResourceServerExtension`** on the resource server.
3. Use the **`declareDiscoveryExtension()`** helper in my route config so my route's `extensions.bazaar` block matches the corrected shape above. The helper auto-generates `info.input.{type, method}` and the JSON Schema, so I should pass it `output: { example, schema }` (and optionally `input: {...}`).
4. Make sure `accepts[0]` declares a supported `network` (Base, Base Sepolia, Polygon, Arbitrum, World, World Sepolia, Solana, or Solana Devnet), an `asset` set to the contract address (or Solana mint) of whatever token you want to be paid in (USDC is the most common choice but is not required), an `amount` ≥ 1000 atomic units ($0.001), and a `payTo` address.

If you need to see specific files (middleware, route handler, package.json, etc.), ask me to share them.