feat(coro): 语言内协程 M1——async def + await + coro_run 状态机

TPC 新增协程生成器 AsyncFunctionHandle（lib/core/Handles/HandlesAsyncFunctions.py）：
async def 编译为帧结构体 {state, done, ret, 局部变量槽} + create_<name>()（malloc
分配）+ resume_<name>()（switch 状态机，0=SUSPEND/1=DONE）。await 按顶层赋值
切分函数体：创建子帧 -> resume -> 取子帧 ret -> 存父帧槽 -> 父挂起（state 前进）；
普通调用 async 函数生成 create（返回帧指针）；coro.coro_run 在调用点内联翻译为
resume 循环。vast parser 已支持语法；新增 includes/coro.vp（Coroutine + 占位
运行时）与 Test/CoroTest（期望输出 coro result = 14）。

M1 限制：async 无参数、返回 i32/int；协程体仅顶层 AnnAssign/Assign/Expr/Return；
await 仅顶层赋值形式、子协程假设一次完成（无嵌套挂起）；coro_run 依赖本模块
先赋值的协程变量。M2 将支持参数/嵌套 await/控制流。

Test/CoroTest/App/main.vp

@@ -0,0 +1,21 @@
+import t, c
+from stdint import *
+import stdio
+import coro
+
+
+async def leaf() -> int:
+    return 7
+
+
+async def task() -> int:
+    a: int = await leaf()
+    b: int = await leaf()
+    return a + b
+
+
+def main() -> t.CInt:
+    tt: coro.Coroutine = task()
+    r: t.CInt = coro.coro_run(tt)
+    stdio.printf("coro result = %d\n", r)
+    return 0

Test/CoroTest/project.json

@@ -0,0 +1,39 @@
+{
+    "$schema": "https://raw.githubusercontent.com/TermiNexus/TransPyC/main/schemas/project-schema.json",
+    "name": "CoroTest",
+    "version": "1.0.0",
+    "source_dir": "./App",
+    "build_dir": "./.tpv_build",
+    "compiler": {
+        "cmd": "llc",
+        "flags": [
+            "-filetype=obj"
+        ]
+    },
+    "linker": {
+        "cmd": "clang++",
+        "flags": [
+            "-Wl,--allow-multiple-definition",
+            "-lmsvcrt",
+            "-lucrt",
+            "-lpthread",
+            "-lmingwex",
+            "-lkernel32",
+            "-luser32"
+        ],
+        "output": "CoroTest.exe"
+    },
+    "includes": [
+        "../../includes"
+    ],
+    "target": {
+        "triple": "x86_64-pc-windows-gnu",
+        "datalayout": "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+    },
+    "options": {
+        "slice_level": 3,
+        "sha1_slice_level": 1,
+        "target": "llvm",
+        "strict_mode": true
+    }
+}