Add Amazon PA API and RapidAPI metadata support

Introduce Amazon PA API and RapidAPI clients for fetching product metadata, with fallback strategies for Amazon URLs.
Add `AmazonMetadataOptions` for configuration and update `RegistryMetadataService` to integrate these clients.
Enhance metadata scraping with ASIN extraction, country code handling, and modern browser headers.
Include deployment files and register new services in `Program.cs`.
Update `appsettings.json` with placeholders for API credentials.

deploy/portainer-stack.yml

@@ -23,6 +23,11 @@ services:
       - Smtp__FromAddress=${SMTP_FROM_ADDRESS}
       - Smtp__FromName=${SMTP_FROM_NAME}
       - PublicUrl=${PUBLIC_URL}
+      - AmazonMetadata__AccessKey=${AMAZON_PA_ACCESS_KEY}
+      - AmazonMetadata__SecretKey=${AMAZON_PA_SECRET_KEY}
+      - AmazonMetadata__AssociateTag=${AMAZON_ASSOCIATE_TAG}
+      - AmazonMetadata__PaApiHost=${AMAZON_PA_API_HOST}
+      - AmazonMetadata__RapidApiKey=${AMAZON_RAPID_API_KEY}
     depends_on:
       - mssql
     networks: