add json subpackage — canonical JSON-RPC numeric types + lowercase codec

Moves the JSON-RPC numeric wrappers (Uint8/16/32/64, Float32/64) and the
gorilla/rpc lowercase Codec helper into the canonical luxfi/utils module.

Replaces github.com/luxfi/codec/jsonrpc which has been retained only as a
historical artefact of the codec module rip. All Lux modules that need
JSON-RPC numeric quoting now have one canonical import:

	import "github.com/luxfi/utils/json"

Identical API to codec/jsonrpc: Uint64.MarshalJSON quotes as decimal string,
NewCodec returns a gorilla/rpc Codec that uppercases the first method letter.

json/codec.go

@@ -0,0 +1,65 @@
+// Copyright (C) 2019-2025, Lux Industries, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+// Package json provides JSON serialization utilities for numeric types and
+// a gorilla/rpc Codec that normalizes lowercase method names.
+package json
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/gorilla/rpc/v2"
+	"github.com/gorilla/rpc/v2/json2"
+)
+
+// Null is the string representation of the JSON null literal.
+const Null = "null"
+
+var (
+	errUppercaseMethod = errors.New("method must start with a non-uppercase letter")
+	errInvalidArg      = errors.New("couldn't unmarshal an argument. Ensure arguments are valid and properly formatted. See documentation for example calls")
+)
+
+// NewCodec returns a new json codec that requires the first character of the
+// method name to be lowercase and upper-cases it for dispatch.
+func NewCodec() rpc.Codec {
+	return lowercase{json2.NewCodec()}
+}
+
+type lowercase struct{ *json2.Codec }
+
+func (lc lowercase) NewRequest(r *http.Request) rpc.CodecRequest {
+	return &request{lc.Codec.NewRequest(r).(*json2.CodecRequest)}
+}
+
+type request struct{ *json2.CodecRequest }
+
+func (r *request) Method() (string, error) {
+	method, err := r.CodecRequest.Method()
+	methodSections := strings.SplitN(method, ".", 2)
+	if len(methodSections) != 2 || err != nil {
+		return method, err
+	}
+	class, function := methodSections[0], methodSections[1]
+	firstRune, runeLen := utf8.DecodeRuneInString(function)
+	if firstRune == utf8.RuneError {
+		return method, nil
+	}
+	if unicode.IsUpper(firstRune) {
+		return method, errUppercaseMethod
+	}
+	uppercaseRune := string(unicode.ToUpper(firstRune))
+	return fmt.Sprintf("%s.%s%s", class, uppercaseRune, function[runeLen:]), nil
+}
+
+func (r *request) ReadRequest(args interface{}) error {
+	if err := r.CodecRequest.ReadRequest(args); err != nil {
+		return errInvalidArg
+	}
+	return nil
+}

json/float32.go

@@ -0,0 +1,29 @@
+// Copyright (C) 2019-2025, Lux Industries, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package json
+
+import "strconv"
+
+// Float32 is a float32 that marshals/unmarshals as a JSON string with 4 digit
+// fixed-point precision.
+type Float32 float32
+
+func (f Float32) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + strconv.FormatFloat(float64(f), 'f', 4, 32) + `"`), nil
+}
+
+func (f *Float32) UnmarshalJSON(b []byte) error {
+	str := string(b)
+	if str == Null {
+		return nil
+	}
+	if len(str) >= 2 {
+		if lastIndex := len(str) - 1; str[0] == '"' && str[lastIndex] == '"' {
+			str = str[1:lastIndex]
+		}
+	}
+	val, err := strconv.ParseFloat(str, 32)
+	*f = Float32(val)
+	return err
+}

json/float64.go

@@ -0,0 +1,28 @@
+// Copyright (C) 2019-2025, Lux Industries, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package json
+
+import "strconv"
+
+// Float64 is a float64 that marshals/unmarshals as a JSON string.
+type Float64 float64
+
+func (f Float64) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + strconv.FormatFloat(float64(f), 'f', -1, 64) + `"`), nil
+}
+
+func (f *Float64) UnmarshalJSON(b []byte) error {
+	str := string(b)
+	if str == Null {
+		return nil
+	}
+	if len(str) >= 2 {
+		if lastIndex := len(str) - 1; str[0] == '"' && str[lastIndex] == '"' {
+			str = str[1:lastIndex]
+		}
+	}
+	val, err := strconv.ParseFloat(str, 64)
+	*f = Float64(val)
+	return err
+}

json/uint16.go

@@ -0,0 +1,28 @@
+// Copyright (C) 2019-2025, Lux Industries, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package json
+
+import "strconv"
+
+// Uint16 is a uint16 that marshals/unmarshals as a JSON string.
+type Uint16 uint16
+
+func (u Uint16) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + strconv.FormatUint(uint64(u), 10) + `"`), nil
+}
+
+func (u *Uint16) UnmarshalJSON(b []byte) error {
+	str := string(b)
+	if str == Null {
+		return nil
+	}
+	if len(str) >= 2 {
+		if lastIndex := len(str) - 1; str[0] == '"' && str[lastIndex] == '"' {
+			str = str[1:lastIndex]
+		}
+	}
+	val, err := strconv.ParseUint(str, 10, 16)
+	*u = Uint16(val)
+	return err
+}

json/uint32.go

@@ -0,0 +1,28 @@
+// Copyright (C) 2019-2025, Lux Industries, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package json
+
+import "strconv"
+
+// Uint32 is a uint32 that marshals/unmarshals as a JSON string.
+type Uint32 uint32
+
+func (u Uint32) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + strconv.FormatUint(uint64(u), 10) + `"`), nil
+}
+
+func (u *Uint32) UnmarshalJSON(b []byte) error {
+	str := string(b)
+	if str == Null {
+		return nil
+	}
+	if len(str) >= 2 {
+		if lastIndex := len(str) - 1; str[0] == '"' && str[lastIndex] == '"' {
+			str = str[1:lastIndex]
+		}
+	}
+	val, err := strconv.ParseUint(str, 10, 32)
+	*u = Uint32(val)
+	return err
+}

json/uint64.go

@@ -0,0 +1,28 @@
+// Copyright (C) 2019-2025, Lux Industries, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package json
+
+import "strconv"
+
+// Uint64 is a uint64 that marshals/unmarshals as a JSON string.
+type Uint64 uint64
+
+func (u Uint64) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + strconv.FormatUint(uint64(u), 10) + `"`), nil
+}
+
+func (u *Uint64) UnmarshalJSON(b []byte) error {
+	str := string(b)
+	if str == Null {
+		return nil
+	}
+	if len(str) >= 2 {
+		if lastIndex := len(str) - 1; str[0] == '"' && str[lastIndex] == '"' {
+			str = str[1:lastIndex]
+		}
+	}
+	val, err := strconv.ParseUint(str, 10, 64)
+	*u = Uint64(val)
+	return err
+}

json/uint8.go

@@ -0,0 +1,28 @@
+// Copyright (C) 2019-2025, Lux Industries, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package json
+
+import "strconv"
+
+// Uint8 is a uint8 that marshals/unmarshals as a JSON string.
+type Uint8 uint8
+
+func (u Uint8) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + strconv.FormatUint(uint64(u), 10) + `"`), nil
+}
+
+func (u *Uint8) UnmarshalJSON(b []byte) error {
+	str := string(b)
+	if str == Null {
+		return nil
+	}
+	if len(str) >= 2 {
+		if lastIndex := len(str) - 1; str[0] == '"' && str[lastIndex] == '"' {
+			str = str[1:lastIndex]
+		}
+	}
+	val, err := strconv.ParseUint(str, 10, 8)
+	*u = Uint8(val)
+	return err
+}