feat: add WASM entry point with renderToString

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/wasm/main.go

@@ -0,0 +1,55 @@
+//go:build js && wasm
+
+package main
+
+import (
+	"syscall/js"
+
+	html "forge.lthn.ai/core/go-html"
+)
+
+func renderToString(_ js.Value, args []js.Value) any {
+	if len(args) < 1 {
+		return ""
+	}
+
+	variant := args[0].String()
+	ctx := html.NewContext()
+
+	if len(args) >= 2 {
+		ctx.Locale = args[1].String()
+	}
+
+	layout := html.NewLayout(variant)
+
+	if len(args) >= 3 && args[2].Type() == js.TypeObject {
+		slots := args[2]
+		for _, slot := range []string{"H", "L", "C", "R", "F"} {
+			content := slots.Get(slot)
+			if content.Type() == js.TypeString && content.String() != "" {
+				switch slot {
+				case "H":
+					layout.H(html.Raw(content.String()))
+				case "L":
+					layout.L(html.Raw(content.String()))
+				case "C":
+					layout.C(html.Raw(content.String()))
+				case "R":
+					layout.R(html.Raw(content.String()))
+				case "F":
+					layout.F(html.Raw(content.String()))
+				}
+			}
+		}
+	}
+
+	return layout.Render(ctx)
+}
+
+func main() {
+	js.Global().Set("gohtml", js.ValueOf(map[string]any{
+		"renderToString": js.FuncOf(renderToString),
+	}))
+
+	select {}
+}