fix(flow): 循环/match 外的 break/continue 改为 fail-fast

- StmtGenDeclMixin：translate_break / translate_continue 增加 node 形参，目标块
  缺失（_break_bb / _continue_bb 为 None）时 fatal_error，不再静默不发跳转
- StmtGenMixin：Break / Continue 分派传入 node（供错误定位）

App/lib/core/Gen/Stmt/StmtGenDeclMixin.vp

@@ -257,8 +257,8 @@ novirtual class StmtGenDeclMixin(StmtGenCifMixin.StmtGenCifMixin):
             return self.translate_nonlocal(trans, node)
         return 0
 
-    def translate_break(self, trans: HT.Translator*) -> int:
-        """翻译 break 语句：跳转到循环 end 块"""
+    def translate_break(self, trans: HT.Translator*, node: ast.AST*) -> int:
+        """翻译 break 语句：跳转到 break 目标（循环 end / match end）"""
         builder: llvmlite.IRBuilder* = trans._cur_builder
         func: llvmlite.Function* = trans._cur_func
         pool: memhub.MemBuddy* = trans.Pool
@@ -266,10 +266,13 @@ novirtual class StmtGenDeclMixin(StmtGenCifMixin.StmtGenCifMixin):
         if builder is None or func is None:
             return 0
 
-        # 发射 br 到 break 目标
-        if trans._break_bb is not None:
-            if llvmlite.builder_cur_block_is_terminated(builder) == 0:
-                llvmlite.build_br(builder, trans._break_bb)
+        # 发射 br 到 break 目标（_break_bb 由循环或 match-case 生成侧设置）
+        if trans._break_bb is None:
+            # fail-fast：没有循环 / match-case 时 break 无处可跳，禁止静默无效果
+            self.Gen.TypeGenErr.fatal_error(node,
+                "break 只能用在循环或 match-case 体内（当前没有可跳出的目标）", "SyntaxError")
+        if llvmlite.builder_cur_block_is_terminated(builder) == 0:
+            llvmlite.build_br(builder, trans._break_bb)
 
         # 创建死代码 BB，用于后续语句（break 后面的代码不可达）
         cnt: int = trans._label_counter
@@ -294,7 +297,7 @@ novirtual class StmtGenDeclMixin(StmtGenCifMixin.StmtGenCifMixin):
                 "fallthrough 只能用在 match-case 语句体内（语义是落到下一个 case）", "SyntaxError")
         return 0
 
-    def translate_continue(self, trans: HT.Translator*) -> int:
+    def translate_continue(self, trans: HT.Translator*, node: ast.AST*) -> int:
         """翻译 continue 语句：跳转到循环 cond/incr 块"""
         builder: llvmlite.IRBuilder* = trans._cur_builder
         func: llvmlite.Function* = trans._cur_func
@@ -304,9 +307,12 @@ novirtual class StmtGenDeclMixin(StmtGenCifMixin.StmtGenCifMixin):
             return 0
 
         # 发射 br 到 continue 目标
-        if trans._continue_bb is not None:
-            if llvmlite.builder_cur_block_is_terminated(builder) == 0:
-                llvmlite.build_br(builder, trans._continue_bb)
+        if trans._continue_bb is None:
+            # fail-fast：循环之外的 continue 无处可跳，禁止静默无效果
+            self.Gen.TypeGenErr.fatal_error(node,
+                "continue 只能用在循环体内（当前没有可继续的循环）", "SyntaxError")
+        if llvmlite.builder_cur_block_is_terminated(builder) == 0:
+            llvmlite.build_br(builder, trans._continue_bb)
 
         # 创建死代码 BB，用于后续语句
         cnt: int = trans._label_counter

App/lib/core/Gen/Stmt/StmtGenMixin.vp

@@ -87,9 +87,9 @@ novirtual class StmtGenMixin(StmtGenDeclMixin.StmtGenDeclMixin):
         elif k == ast.ASTKind.Pass:
             return 0
         elif k == ast.ASTKind.Break:
-            return self.translate_break(trans)
+            return self.translate_break(trans, node)
         elif k == ast.ASTKind.Continue:
-            return self.translate_continue(trans)
+            return self.translate_continue(trans, node)
         elif k == ast.ASTKind.FallThrough:
             return self.translate_fallthrough(trans, node)
         elif k == ast.ASTKind.Match: