refactor(tpv): rowptr[T] 迁移 + D 表定长缓冲改精确分配 + SHA1 前缀判定收敛（D1/D3/D4/D5/D6/D7/C10）

Test/App/nested_match_test.vp

@@ -17,7 +17,7 @@ import string
 # ============================================================
 
 # 内存池（测试内部使用）
-_mbuddy: memhub.MemBuddy | t.CPtr
+_mbuddy: rowptr[memhub.MemBuddy]
 
 # 测试用内存大小（64KB，足够构造 LLVMType 值）
 _NMATCH_POOL_SIZE: t.CDefine = 65536
@@ -32,7 +32,7 @@ def _init_mbuddy() -> int:
     if arena is None:
         stdio.printf("FAIL: malloc for arena failed\n")
         return 1
-    mb: memhub.MemBuddy | t.CPtr = stdlib.malloc(memhub.MemBuddy.__sizeof__())
+    mb: rowptr[memhub.MemBuddy] = stdlib.malloc(memhub.MemBuddy.__sizeof__())
     stdio.printf("[DBG] _init_mbuddy: malloc mb=%d\n", mb is None)
     if mb is None:
         stdio.printf("FAIL: MemBuddy init failed\n")

Test/Sha1Test/App/main.vp

@@ -14,7 +14,7 @@ def main() -> int:
     arena: bytes = stdlib.malloc(POOL_SIZE)
     if arena is None:
         return 1
-    mb: memhub.MemBuddy | t.CPtr = memhub.MemBuddy(arena, POOL_SIZE)
+    mb: rowptr[memhub.MemBuddy] = memhub.MemBuddy(arena, POOL_SIZE)
     if mb is None:
         return 1
     hashlib._mbuddy = (memhub.MemManager | t.CPtr)(mb)