feat: 生成器基础支持（YIELD 帧快照挂起/恢复 + GeneratorPrototype next/return/throw）

- 新增 YIELD/SUSPEND_BODY opcode；function* 识别与 yield emit
- GeneratorState 全量快照 VM 执行上下文（regs/pc/bytecode/spill/save/try/cell 栈段/迭代器）
- 调用时参数初始化（默认值/解构副作用与异常在 g() 时刻生效）
- %GeneratorPrototype%/%GeneratorFunction.prototype% 内建对象与 next/return/throw
- session GC trace 生成器状态 JsValues；闭包捕获分析补 yield/赋值目标扫描

crates/oxide_bytecode/src/opcode.rs

@@ -189,7 +189,7 @@ define_opcodes! {
     PROFILE_BRANCH = 0x6B => "PROFILE_BRANCH",
     PROFILE_CALL = 0x6C => "PROFILE_CALL",
 
-    // ── 并行 — 占位符 (0x70-0x7F) ──
+    // ── 并行 — 占位符 (0x70-0x75) ──
     FORK = 0x70 => "FORK",
     JOIN = 0x71 => "JOIN",
     GET_PRIVATE = 0x72 => "GET_PRIVATE",
@@ -197,6 +197,11 @@ define_opcodes! {
     INIT_PRIVATE = 0x74 => "INIT_PRIVATE",
     PRIVATE_BRAND_IN = 0x75 => "PRIVATE_BRAND_IN",
 
+    // ── 生成器 (0x76-0x77) ──
+    YIELD = 0x76 => "YIELD", // rd=被让出的值（结果经 reg 0 交付，见 contract.rs）
+    // 生成器 body 起点标记：调用时参数初始化完成后挂起于此，首次 next() 从这继续。
+    SUSPEND_BODY = 0x77 => "SUSPEND_BODY",
+
     // ── 位运算 (0x80-0x8F) ──
     BIT_AND = 0x80 => "BIT_AND",
     BIT_OR = 0x81 => "BIT_OR",