feat(coro): M2——async 参数/嵌套 await 表达式/If-While 控制流

- 帧结构体增加参数槽与提升临时变量槽，create_<name> 带参数存入帧
- 嵌套 await（如 a = b + await f()）提升为顶层临时赋值 __await_N，帧预留槽
- 协程版 If/While：条件求值 + 分支内 await 就地挂起/恢复（动态状态号恢复块）
- For 循环委托现有 handler（仅支持无 await/return，M3 扩展）
- CoroTest 用例覆盖参数/嵌套 await/while+await/if+await（期望 coro result = 30）

Test/CoroTest/App/main.vp

@@ -4,18 +4,25 @@ import stdio
 import coro
 
 
-async def leaf() -> int:
-    return 7
+async def leaf(x: int) -> int:
+    return x + 1
 
 
-async def task() -> int:
-    a: int = await leaf()
-    b: int = await leaf()
-    return a + b
+async def task(base: int) -> int:
+    a: int = await leaf(base)
+    b: int = a * 2 + await leaf(a)
+    s: int = 0
+    i: int = 0
+    while i < 3:
+        s = s + await leaf(i)
+        i = i + 1
+    if s > 5:
+        s = s + await leaf(10)
+    return s + a + b
 
 
 def main() -> t.CInt:
-    tt: coro.Coroutine = task()
+    tt: coro.Coroutine = task(2)
     r: t.CInt = coro.coro_run(tt)
     stdio.printf("coro result = %d\n", r)
-    return 0
+    return 0