Lovable

Add ChatAds affiliate link monetization to this app.

**What ChatAds does:** I send it a text message (like a chat response or article
paragraph) and it returns affiliate links for any products mentioned in that text.

**What I need:**

1. A server-side function called `chatads-proxy` that:
   - Accepts POST requests with `{ "message": string }` in the body
   - Calls `POST https://api.getchatads.com/v1/chatads/messages` with the message,
     passing `x-api-key: cak_your_api_key` in the headers
   - Returns the API response to the client
   - Handles CORS for the frontend origin

2. On the frontend, after generating or displaying text content:
   - Call the `chatads-proxy` function with the text as the `message`
   - The response looks like this:
     ```json
     {
       "data": {
         "returned": 1,
         "offers": [{
           "link_text": "standing desk",
           "url": "https://amazon.com/...",
           "product": {
             "title": "Standing Desk, Adjustable Height...",
             "stars": 4.5,
             "reviews": 2340
           }
         }]
       }
     }
     ```
   - If `data.returned > 0`, find the first `link_text` in the displayed text and
     replace it with a hyperlink using the `url`. Open links in a new tab.
   - If `data.returned === 0` or there's an error, show the original text unchanged.

Don't show loading states for the ChatAds call. Display the text immediately and
update with affiliate links when the response arrives.

Show me the chatads-proxy function code so I can verify the API key
is being sent correctly in the x-api-key header.

The chatads-proxy function is returning CORS errors. Make sure it
handles OPTIONS preflight requests and returns the correct CORS headers
for my frontend origin.