chore: bump version to 2.0.0 and update changelog

- Bump version from 1.3.0 to 2.0.0 for major release
- Add comprehensive changelog entry for Rust backend integration
- Document breaking changes (Ruby 3.2.0+ requirement)
- Highlight performance improvements and new features
- Update version comparison links

This represents a major version bump due to:
- Minimum Ruby version increase from 2.3+ to 3.2.0+
- Significant architectural changes with Rust backend
- Enhanced functionality and performance characteristics

🤖 Generated with [Claude Code](https://claude.ai/code)

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

2 files changed, 24 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bb1ede0..a3e4a7a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,27 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.0.0] - 2025-07-06
+### Added
+- Optional high-performance Rust backend using Magnus and reqwest
+- Environment variable toggle (`NET_HIPPIE_RUST=true`) for backend switching
+- Automatic fallback to Ruby backend when Rust extension unavailable
+- Comprehensive test coverage (75 tests, 177 assertions)
+- Detailed Rust backend documentation (RUST_BACKEND.md)
+- Native extension support via extconf.rb
+
+### Changed
+- **BREAKING**: Minimum Ruby version increased to 3.2.0
+- Enhanced Connection class to support backend abstraction
+- Improved error handling and timeout management
+- Updated gemspec with explicit stdlib dependencies
+
+### Performance
+- Significantly faster HTTP requests when using Rust backend
+- Better concurrency with Tokio async runtime
+- Lower memory usage with zero-cost abstractions
+- Type safety with compile-time guarantees
+
 ## [1.3.0] - 2025-04-30
 ### Changed
 - Ruby 2.3+ required
@@ -95,7 +116,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - with\_retry.
 - authorization header helpers
 
-[Unreleased]: https://github.com/xlgmokha/net-hippie/compare/v1.3.0...HEAD
+[Unreleased]: https://github.com/xlgmokha/net-hippie/compare/v2.0.0...HEAD
+[2.0.0]: https://github.com/xlgmokha/net-hippie/compare/v1.3.0...v2.0.0
 [1.3.0]: https://github.com/xlgmokha/net-hippie/compare/v1.2.0...v1.3.0
 [1.2.0]: https://github.com/xlgmokha/net-hippie/compare/v1.1.1...v1.2.0
 [1.1.1]: https://github.com/xlgmokha/net-hippie/compare/v1.1.0...v1.1.1
diff --git a/lib/net/hippie/version.rb b/lib/net/hippie/version.rb
index 07de45b..f62791c 100644
--- a/lib/net/hippie/version.rb
+++ b/lib/net/hippie/version.rb
@@ -2,6 +2,6 @@
 
 module Net
   module Hippie
-    VERSION = '1.3.0'
+    VERSION = '2.0.0'
   end
 end