0.3.0

Changed

• Improved lookup performance by using a generic bounded key cache for decoded map keys.
• Improved IPAddr lookup performance by decoding packed bytes from IPAddr#hton directly.
• Switched map-key cache hashing to FxHashMap for faster key-cache access.
• Switched map-key cache roots to a Ruby-owned cache array with Rust key-to-index lookups.
• Refactored duplicated prefix and within decode paths in the Rust reader for simpler maintenance.
• Refactored duplicate database file-open error handling shared by MMAP and MEMORY modes.
• Updated Rust and Ruby dependencies.
• Added Ruby 4.0 coverage to CI workflows.

Fixed

• Made extension initialization idempotent across MaxMind::DB class/module loading modes to avoid typed-data incompatibility when the extension is loaded more than once.
• When loaded with the official MaxMind::DB class, MaxMind::DB::Rust now uses anonymous module creation to preserve canonical module naming.
• Scoped Rust dependency cache per Ruby version in CI tests and stopped caching target/ in the test workflow to avoid cross-version artifact contamination.