Add conformant .NET implementation

[Jason-Doyle]

Summary

• add independent WorldCut and WorldCut.Tool 0.1.0 packages for net8.0 and net10.0
• implement the complete protocol 0.1 / engine 0.1.2 verifier, immutable public models, exact planner semantics, year-zero timestamps, CLI, and full golden-result digests
• vendor the audited MIT Jcs.NET 0.1.1 canonicalizer at commit 8aff616 with explicit attribution, verified upstream hashes, and WorldCut-owned Unicode/duplicate/depth handling
• add locked/audited NuGet restore, strict analyzers, dual-OS CI, package allowlists and isolated consumers, C# CodeQL, and NuGet Dependabot

Quality gate

• 548 tests pass across net8.0 and net10.0
• zero warnings under latest-all analyzers with warnings as errors
• full conformance corpus and manifest hashes pass
• differential review found zero differences across 10,249 targeted/randomized TypeScript comparisons
• isolated library packages and worldcut-dotnet tool pass on both frameworks
• vendored-source provenance is mechanically reconstructed and hash-verified
• root release checks, Python tests, Go tests/vet/race, and actionlint pass

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