Fuse v3.1.0

What's Changed

• Fuse 3.0.0: retrieval, packing, routing, and honest benchmarking by @litenova in #19
• Fuse V3: Roslyn-backed .NET semantic context engine (benchmarks, docs, publish readiness) by @litenova in #20
• V3.1: open-ended floor (S3 signal-sufficiency contract first) by @litenova in #21

Full Changelog: v2.4.0...v3.1.0