Prepare for release of version 3.0.0

[th3hero]

This pull request introduces a major new release (v3.0.0) of Express Storage, focusing on breaking changes, improved type safety, modularity, and developer experience. The most important updates include making cloud SDKs optional peer dependencies, refactoring result types to discriminated unions, removing presigned driver subclasses, and updating the documentation and workflows to match the new requirements.

Breaking API and Dependency Changes

• Cloud SDKs (AWS, GCS, Azure) are now optional peer dependencies. Consumers must install only the SDKs needed for their chosen provider, reducing dependency bloat for local-only users. [1] [2]
• Result types (FileUploadResult, DeleteResult, etc.) are now discriminated unions with a success: true | false flag, improving TypeScript narrowing and error handling.
• Presigned driver subclasses (S3PresignedStorageDriver, etc.) have been removed; base driver classes now handle both direct and presigned modes internally.
• Several method and field renames for consistency: .fileName → .reference across result types, and rateLimit → rateLimiter in options.
• All filesystem operations are now fully async, ensuring non-blocking behavior under concurrent load.

Documentation and Developer Experience

• The README.md has been extensively rewritten to clarify features, quick start, error codes, API reference, and migration instructions. It now explicitly instructs users to install only the required cloud SDKs. [1] [2] [3] [4]
• New sections in the documentation highlight error codes for programmatic handling, improved examples, and details about type-safe results and configuration. [1] [2] [3]

CI/CD and Node Version Updates

• GitHub workflow files (publish.yml, push.yml) have been updated to use Node.js 22.x for all jobs, aligning with the new minimum engine requirement. [1] [2] [3]

Changelog and Release Management

• The CHANGELOG.md has been completely rewritten to document all breaking changes, new features, removals, and migration guidance for v3.0.0.

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References:
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]