Remove JsonValue.fs from client and migrate to System.Text.Json

[Copilot]

The custom JsonValue.fs deserializer inferred numeric types from JSON structure rather than the GraphQL schema, causing schema-declared Float fields returning 0.0 to be deserialized as int option instead of float option.

Core fix

JsonValueHelper.getFieldValue in BaseTypes.fs now resolves the CLR type from the schema IntrospectionTypeRef when handling JsonValueKind.Number, ensuring Float 0 → float, Int 0 → int, etc.

| JsonValueKind.Number ->
    // Use the schema type to determine the correct numeric CLR type
    let innerTypeRef =
        match schemaField.SchemaTypeRef.Kind with
        | TypeKind.NON_NULL -> schemaField.SchemaTypeRef.OfType |> Option.get
        | _ -> schemaField.SchemaTypeRef
    let numVal = getNumericValue innerTypeRef fieldValue
    makeSomeIfNeeded numVal

Removed

• JsonValue.fs and TextConversions.fs removed from both FSharp.Data.GraphQL.Client and FSharp.Data.GraphQL.Client.DesignTime project files

Replaced with System.Text.Json

• Serialization.fs: New SchemaParser module manually traverses JsonElement to parse the introspection schema. Exposes defaultSerializerOptions (lazy, backed by Shared.Json.getSerializerOptions). Request JSON building uses JsonSerializer.Serialize via a normalizeForSerialization pre-processor that handles camelCase key normalization on nested IDictionary<string,obj> values, System.Uri → string, and Upload → form-part name. deserializeMap uses JsonElement.
• BaseTypes.fs (JsonValueHelper): All pattern matching rewritten from JsonValue DU cases to JsonElement.ValueKind.
• OperationResultBase: Now accepts the raw response string and parses it internally with JsonDocument (implements IDisposable); removes the JsonValue.Parse call from ProvidedTypesHelper.fs.
• GraphQLClient.fs: Request/multipart construction rewritten; variables serialized via JsonSerializer.Serialize with the context's JsonSerializerOptions.
• GraphQLProviderRuntimeContext: Exposes a JsonSerializerOptions property (defaults to defaultSerializerOptions) so callers can inject custom options (e.g. custom scalar converters). GetContext accepts an optional jsonSerializerOptions parameter.

Test updates

OperationErrorTests.fs: JsonValue.Parse calls replaced with raw JSON strings, matching the new OperationResultBase(string) constructor.

[xperiandri]

What is the sense of having so much custom logic?
Cannще we pass JsonSerializerOptions into context and use JsonSerialzer to serialize and JsonSerialzer or JsonDocument/JsonElement to deserialize? Anyway we have already built the output types in the type provider

[Copilot]

What is the sense of having so much custom logic?
Cannще we pass JsonSerializerOptions into context and use JsonSerialzer to serialize and JsonSerialzer or JsonDocument/JsonElement to dese...

Good point. Implemented in commit 9f7f617:

• JsonSerializerOptions is now a property on GraphQLProviderRuntimeContext (defaults to Serialization.defaultSerializerOptions.Value)
• GetContext accepts an optional jsonSerializerOptions parameter so callers can inject custom options (e.g. with custom scalar converters)
• buildRequestJson now takes JsonSerializerOptions and uses JsonSerializer.Serialize for the variables object
• A normalizeForSerialization helper pre-processes variable values before handing them to JsonSerializer.Serialize to handle edge cases that STJ doesn't cover out of the box (camelCase key normalization on nested IDictionary<string,obj> values, System.Uri → string, Upload → file name string)

The result is that the bulk of the variable serialization is now done by JsonSerializer with the provided options, and users can customize it by passing their own JsonSerializerOptions to GetContext.