feat(cloudflare): add R2 multipart upload with streaming and S3 credentials support

[austinm911]

Summary

This PR adds comprehensive multipart upload support to the R2Bucket resource, enabling efficient handling of large files (100MB+) with streaming capabilities and S3-compatible credentials.

Features

S3-Compatible Credentials Support

• Added accessKeyId, secretAccessKey, and sessionToken properties to CloudflareApiOptions
• Implemented R2S3Client for S3-compatible multipart upload operations
• Enables use of R2's S3-compatible API for advanced upload scenarios

Streaming Support for Multipart Uploads

• Node.js Readable stream support for efficient memory usage
• Optional size parameter to enable streaming without buffering entire file into memory
• Miniflare compatibility for local development and testing
• Type guards for duck-typed Headers, Blob, and ReadableStream

Use Cases

• Upload large files from Workers without loading entire file into memory
• Stream data directly from external sources
• Handle production workloads with efficient memory management
• Test multipart upload workflows locally with Miniflare

Code Example

import { R2Bucket } from "alchemy/cloudflare";
import { alchemy } from "alchemy";

const app = await alchemy("my-app");

const bucket = await R2Bucket("my-bucket", {
  name: "my-data-bucket",
  accessKeyId: alchemy.secret.env.R2_ACCESS_KEY_ID,
  secretAccessKey: alchemy.secret.env.R2_SECRET_ACCESS_KEY,
});

// Upload with streaming support
await bucket.multipartUpload({
  key: "large-file.bin",
  value: readableStream,
  size: 104857600, // 100MB - enables streaming
  httpMetadata: {
    contentType: "application/octet-stream",
  },
});

Changes

• alchemy/src/cloudflare/bucket.ts: Enhanced with multipart upload streaming support
• alchemy/src/cloudflare/r2-s3-client.ts: New S3 client implementation
• alchemy/src/cloudflare/api.ts: Added S3 credential properties
• alchemy/test/cloudflare/bucket.test.ts: Comprehensive test coverage
• alchemy-web/content/docs/providers/cloudflare/bucket.md: Updated documentation

Testing

• ✅ Local development with Miniflare
• ✅ Streaming upload tests
• ✅ S3 credentials integration tests
• ✅ Worker integration examples

🤖 Generated with Claude Code

Co-Authored-By: Claude noreply@anthropic.com

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✨ Finishing touches

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commit: 0ae8105

[austinm911]

@austinm911 need to remove