refactor: 寄存器号 u8→u32 全链放宽，vreg 化去 checkpoint/reg_overflow

crates/oxide_emit/src/expr/template/mod.rs

@@ -7,7 +7,7 @@ mod tagged;
 mod template_literal;
 
 impl Emitter {
-    pub(crate) fn emit_template_domain(&self, expr: &Expression, ctx: &mut CompileCtx) -> Result<u8, String> {
+    pub(crate) fn emit_template_domain(&self, expr: &Expression, ctx: &mut CompileCtx) -> Result<u32, String> {
         match expr {
             Expression::TemplateLiteral(tl) => self.emit_template_literal_expression(tl, ctx),
             Expression::TaggedTemplateExpression(tt) => self.emit_tagged_template_expression(tt, ctx),