refactor: 拆分 oxide_emit 为独立 emit pass crate（依赖倒置）

crates/oxide_emit/src/stmt/basic/labeled.rs

@@ -0,0 +1,32 @@
+use crate::{CompileCtx, Emitter};
+use oxide_parser::Statement;
+
+impl Emitter {
+    fn is_iteration_statement(stmt: &Statement) -> bool {
+        matches!(
+            stmt,
+            Statement::WhileStatement(_)
+                | Statement::DoWhileStatement(_)
+                | Statement::ForStatement(_)
+                | Statement::ForInStatement(_)
+                | Statement::ForOfStatement(_)
+        )
+    }
+
+    pub(crate) fn emit_labeled_statement(
+        &self, stmt: &oxide_parser::LabeledStatement, ctx: &mut CompileCtx,
+    ) -> Result<Option<u8>, String> {
+        let name = stmt.label.name.as_str();
+        if Self::is_iteration_statement(&stmt.body) {
+            ctx.queue_loop_label(name)?;
+            self.emit_statement(&stmt.body, ctx)?;
+        } else {
+            let id = ctx.next_label_id();
+            ctx.push_label_scope(name, id, None)?;
+            self.emit_statement(&stmt.body, ctx)?;
+            ctx.labels.set_label_pos(id, ctx.insts.len());
+            ctx.pop_label_scope();
+        }
+        Ok(None)
+    }
+}