Add .NET 10 Native AOT support with static protocol metadata

[alsi-lawr]

Why this shape: Native AOT requires static metadata, not merely System.Text.Json

This adds a net10.0 Native AOT path while preserving the existing netstandard2.0 package and API. The modern asset uses generated JSON metadata, static RPC registration and the existing protocol model/routes; legacy Newtonsoft/JToken and dynamic APIs remain compatibility-only.

Evidence

• 99/99 net8 and 1/1 net10 tests pass with zero warnings or errors.
• Exact netstandard API compatibility; zero unapproved net10 drift.
• All 72 routes retain their methods, order and static mappings.
• Fresh and locked package restore, audit, pack, warning-free Native AOT publish and native execution pass.
• The package contains both target assets and one implementation-only metadata assembly.

Trade-offs

• Net10 intentionally omits legacy Newtonsoft/JToken APIs.
• F# reflection-free compilation omits 365 generated structural ToString declarations while retaining intentional behaviour.
• Static AOT support adds a generation step and support assembly (rather than hiding reflection behind suppressions), but avoids a custom transport or parallel protocol model.