feat(cloudflare): add custom domain support for R2 buckets

alchemy-web/src/content/docs/providers/cloudflare/bucket.md

@@ -65,6 +65,50 @@ console.log(publicBucket.domain); // [random-id].r2.dev
 
 This enables the `r2.dev` domain for the bucket. This URL is rate-limited and not recommended for production use.
 
+## With Custom Domain
+
+Serve bucket content through your own domain with automatic DNS configuration:
+
+```ts
+import { R2Bucket, Zone } from "alchemy/cloudflare";
+
+// Option 1: Using a Zone resource (domain can be derived from zone)
+const zone = await Zone("my-zone", { name: "example.com" });
+
+const cdnBucket = await R2Bucket("cdn-assets", {
+  name: "cdn-assets",
+  customDomain: {
+    domain: "cdn.example.com", // Optional when using Zone resource
+    zone: zone, // Pass the Zone resource directly
+    enabled: true,
+    minTLS: "1.2", // Minimum TLS version (1.0, 1.1, 1.2, 1.3)
+  },
+});
+
+// Option 2: Using a zone ID string (domain is required)
+const cdnBucket2 = await R2Bucket("cdn-assets-2", {
+  name: "cdn-assets-2",
+  customDomain: {
+    domain: "cdn2.example.com", // Required when using zone ID string
+    zone: "your-zone-id", // Cloudflare Zone ID as string
+    enabled: true,
+    minTLS: "1.2",
+  },
+});
+
+// DNS record is automatically created as a proxied CNAME to public.r2.dev
+console.log(cdnBucket.customDomain?.domain); // "cdn.example.com"
+```
+
+The custom domain feature:
+
+- Automatically creates a proxied CNAME DNS record pointing to `public.r2.dev`
+- Handles DNS record cleanup when the custom domain is removed
+- Supports TLS configuration and cipher suite customization
+- Provides ownership verification and SSL certificate status
+- Accepts either a Zone resource or zone ID string for the `zone` property
+- When using a Zone resource, the `domain` can be derived from the zone's name if not explicitly provided
+
 ## With CORS
 
 Create a bucket with CORS rules:
@@ -210,7 +254,6 @@ const bucket = await R2Bucket("my-bucket", {
 });
 ```
 
-
 ### `head`
 
 Retrieve metadata about an object.
@@ -254,4 +297,4 @@ List objects in the bucket.
 ```ts
 const list = await bucket.list();
 console.log(list.objects.length);
-```
+```