fix(global): 修复存储结构体字段零值文本的池缓冲溢出

_stg_field_zero_text 分配 160 字节，却用 snprintf(buf, 576, ...) 写出，长类型文本
（如 !llvm.array<8 x i8> zeroinitializer）可越界 415 字节，写穿相邻空闲块的元数据，
触发 [MEM] _fl_pop / [FREEFRAME] 空闲块被写穿（内核编译在 PhaseA 45/50 处中断）。
按实际类型文本长度分配（strlen+24），并把 snprintf 上限与分配对齐。

本文件同时含 3 处 DETSITE 插桩（elem_ty_str_n / ty_str / ty_buf_v）。

App/lib/core/Gen/TranslatorGenMixin.vp

@@ -182,7 +182,7 @@ novirtual class TranslatorGenMixin:
                 pos_n: sizet = sizet(written_n)
                 # Sub-array type prefix (e.g. "[16 x i8]"): nested initializers must spell out the
                 # inner type, so serialize elem_ty via TypePrint for the [[16 x i8][...]] form.
-                elem_ty_str_n: str = pool.alloc(4096)
+                elem_ty_str_n: str = pool.alloc_tagged(4096, memhub.DETSITE_TRANSLATORGEN_185)
                 if elem_ty_str_n is None: return None
                 mlirlite.TypePrint(elem_ty_str_n, 4096, elem_ty, pool)
                 for i_n in range(cnt_total_n):
@@ -318,18 +318,22 @@ novirtual class TranslatorGenMixin:
     def _stg_field_zero_text(self, pool: memhub.MemBuddy*, fty: mlirlite.LLVMType*, ty_str: str) -> str:
         """Build the zero initializer text for a storage struct field by LLVM type."""
         if fty is None or ty_str is None: return None
-        buf: str = pool.alloc(160)
+        # Size by the actual type text: TypePrint inlines full struct bodies (up to 4096 bytes), and
+        # the historic fixed 160-byte buffer was written with a 576-byte snprintf limit, so a long
+        # type text overflowed the pool block and corrupted the neighbouring free block.
+        cap: sizet = string.strlen(ty_str) + 24
+        buf: str = pool.alloc(cap)
         if buf is None: return None
         match fty:
             case mlirlite.LLVMType.Ptr(_):
-                viperlib.snprintf(buf, 576, "%s null", ty_str)
+                viperlib.snprintf(buf, cap, "%s null", ty_str)
             case mlirlite.LLVMType.Int(_):
-                viperlib.snprintf(buf, 576, "%s 0", ty_str)
+                viperlib.snprintf(buf, cap, "%s 0", ty_str)
             case mlirlite.LLVMType.Float(_):
-                viperlib.snprintf(buf, 576, "%s 0.0", ty_str)
+                viperlib.snprintf(buf, cap, "%s 0.0", ty_str)
             case _:
                 # Aggregates such as Array / Struct -> zeroinitializer
-                viperlib.snprintf(buf, 576, "%s zeroinitializer", ty_str)
+                viperlib.snprintf(buf, cap, "%s zeroinitializer", ty_str)
         return buf
 
     # _default_val_const_text - field default value -> LLVM constant element text; only foldable
@@ -381,7 +385,7 @@ novirtual class TranslatorGenMixin:
             fe: GenTypes.FieldEntry* = self.Gen.StructGen._get_field_entry(se, i)
             i += 1
             if fe is None or fe.Ty is None: continue
-            ty_str: str = pool.alloc(4096)
+            ty_str: str = pool.alloc_tagged(4096, memhub.DETSITE_TRANSLATORGEN_384)
             if ty_str is None: continue
             mlirlite.TypePrint(ty_str, 4096, fe.Ty, pool)
             elem: str = self._default_val_const_text(pool, fe.Ty, ty_str, fe.DefaultVal)
@@ -829,7 +833,7 @@ novirtual class TranslatorGenMixin:
                                 for fi_v in range(1, fc_v):
                                     fe_v: GenTypes.FieldEntry* = self.Gen.StructGen._get_field_entry(resolved_stg_entry, fi_v)
                                     if fe_v is None or fe_v.Ty is None: continue
-                                    ty_buf_v: str = pool.alloc(4096)
+                                    ty_buf_v: str = pool.alloc_tagged(4096, memhub.DETSITE_TRANSLATORGEN_832)
                                     if ty_buf_v is None: continue
                                     mlirlite.TypePrint(ty_buf_v, 4096, fe_v.Ty, pool)
                                     zero_v: str = self._stg_field_zero_text(pool, fe_v.Ty, ty_buf_v)