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

HandlesBody：loop_break_targets / loop_continue_targets 为空时不再静默不生成跳转，
直接 FailFastError 暴露——原实现会让 break/continue 无声无效果（不兜底原则）。

lib/core/Handles/HandlesBody.py

@@ -41,11 +41,20 @@ class BodyHandle(BaseHandle):
                 elif isinstance(Node, ast.While):
                     self.Trans.WhileHandler._HandleWhileLlvm(Node)
                 elif isinstance(Node, ast.Break):
-                    if Gen.loop_break_targets:
-                        Gen.builder.branch(Gen.loop_break_targets[-1])
+                    if not Gen.loop_break_targets:
+                        # fail-fast：循环 / match-case 之外的 break 无处可跳，
+                        # 静默忽略只会让"提前退出"变成无声无效果（不兜底）
+                        from lib.core.LLVMCG.FuncGen import FailFastError
+                        raise FailFastError(
+                            "break 只能用在循环或 match-case 体内（当前没有可跳出的目标）")
+                    Gen.builder.branch(Gen.loop_break_targets[-1])
                 elif isinstance(Node, ast.Continue):
-                    if Gen.loop_continue_targets:
-                        Gen.builder.branch(Gen.loop_continue_targets[-1])
+                    if not Gen.loop_continue_targets:
+                        # fail-fast：循环之外的 continue 无处可跳（同上）
+                        from lib.core.LLVMCG.FuncGen import FailFastError
+                        raise FailFastError(
+                            "continue 只能用在循环体内（当前没有可继续的循环）")
+                    Gen.builder.branch(Gen.loop_continue_targets[-1])
                 elif isinstance(Node, ast.With):
                     self.Trans.WithHandler._HandleWithLlvm(Node)
                 elif isinstance(Node, ast.ClassDef):