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

crates/oxide_emit/src/class/field.rs

@@ -0,0 +1,40 @@
+use crate::{CompileCtx, Emitter};
+use oxide_ir::operand::Operand;
+use oxide_parser::{ClassElement, PropertyKey};
+
+impl Emitter {
+    /// Emit static field initializers and static blocks in source order.
+    /// JS class semantics interleave them (e.g. `static x = 1; static {
+    /// this.y = 1 } static z = this.y + 1` must run in that order). Emitting
+    /// all fields before all blocks would make `z` read `y` before it is set.
+    pub(crate) fn emit_class_static_elements(
+        &self, elements: &[ClassElement], ctor_reg: u8, ctx: &mut CompileCtx,
+    ) -> Result<(), String> {
+        let saved_static_this = ctx.static_block_this_reg;
+        ctx.static_block_this_reg = Some(ctor_reg);
+        for element in elements {
+            match element {
+                ClassElement::PropertyDefinition(prop) => {
+                    let prop = prop.as_ref();
+                    if prop.r#static {
+                        if let PropertyKey::PrivateIdentifier(private) = &prop.key {
+                            self.emit_private_field_init(Operand::Reg(ctor_reg as u32), private.name.as_str(), prop.value.as_ref(), ctx)?;
+                        } else {
+                            self.emit_public_field_init(Operand::Reg(ctor_reg as u32), &prop.key, prop.computed, prop.value.as_ref(), ctx)?;
+                        }
+                    }
+                }
+                ClassElement::StaticBlock(block) => {
+                    ctx.push_scope();
+                    for stmt in &block.body {
+                        self.emit_statement(stmt, ctx)?;
+                    }
+                    ctx.pop_scope();
+                }
+                _ => {}
+            }
+        }
+        ctx.static_block_this_reg = saved_static_this;
+        Ok(())
+    }
+}