Add deterministic adapter run snapshots

[woksin]

Summary

Adds a deterministic, fail-closed adapter execution boundary that freezes and validates every contribution before neutral resolution while preserving all legacy adapter and generator APIs.

Added

• Add source-neutral adapter descriptors, capabilities, structured probes, immutable run snapshots, and atomic contribution admission. (Define adapter descriptors, structured probes, and frozen contribution admission #23)
• Add an exactly-once deterministic .NET adapter runner with modern and legacy registrations, source authority, version and capability enforcement, and isolated failures. (Define adapter descriptors, structured probes, and frozen contribution admission #23)
• Add snapshot-aware generation with per-fact lowered, provenance-only, omitted, conflicted, or fail-closed dispositions. (Define adapter descriptors, structured probes, and frozen contribution admission #23)

Changed

• Add a modern Vogen descriptor and structured probe while preserving legacy contribution bytes. (Define adapter descriptors, structured probes, and frozen contribution admission #23)
• Document explicit adapter rosters, migration guidance, and the boundaries with derivation lineage and realization reports. (Define adapter descriptors, structured probes, and frozen contribution admission #23)
• Verify the complete surface through candidate-only consumers and unchanged legacy binaries. (Define adapter descriptors, structured probes, and frozen contribution admission #23)