v0.3.0

What's new

Type safety and correctness

• Domain newtypes, improved error model, and secret redaction
• Replaced custom Scalar with DataFusion's ScalarValue
• 9 type-driven fixes for correctness, safety, and design

Robustness

• Enforced boundary contracts for API response shape and multi-spec resolution
• Replaced assert! in AcceptHeader::new with Result
• Resolved all clippy warnings across both crates

Docs

• Rewrote README