Consolidate introspection schema, diagnostics transport, and JSON float-literal updates

[Copilot]

Added

• Added payloadSchema to command introspection metadata output. (Add payload and argument schema metadata to introspection endpoints #2258)
• Added argumentsSchema to query introspection metadata, including required argument fields. (Add payload and argument schema metadata to introspection endpoints #2258)
• Added Arc.Core round-trip specs for plain numbers, NaN, Infinity, and -Infinity. (Allow named floating-point literals in Arc JSON defaults #2263)

Changed

• Switched introspection schema generation to Arc serializer options for consistent metadata contracts. (Add payload and argument schema metadata to introspection endpoints #2258)
• Extended query parameter metadata to carry requiredness in model-bound and controller performers. (Add payload and argument schema metadata to introspection endpoints #2258)
• Enabled named floating-point literals in Arc JSON defaults via JsonNumberHandling.AllowNamedFloatingPointLiterals. (Allow named floating-point literals in Arc JSON defaults #2263)

options.NumberHandling = JsonNumberHandling.AllowNamedFloatingPointLiterals;

Fixed

• Eliminated React Native/Hermes failure risk by removing CustomEvent usage from diagnostics snapshot publishing. (ObservableQueryDiagnostics crashes on React Native / Hermes due to missing CustomEvent #2260)

[github-actions]

NuGet packages for this PR, e.g. Cratis.Arc:
https://github.com/cratis/arc/packages/1655206?version=20.32.0

[github-actions]

NuGet packages for this PR, e.g. Cratis.Arc:
https://github.com/cratis/arc/packages/1655206?version=20.33.0