refactor: 移除模板变量 {{change-name}} 替换功能，模板改为纯静态文本

tests/integration/flow.test.ts

@@ -115,7 +115,7 @@ stages:
     documents:
       - name: spec
         prompt: 生成规格文档
-        template: "# {{change-name}} 规格"
+        template: "# 规格文档"
 `,
     );
 
@@ -127,7 +127,7 @@ stages:
     await mkdir(getChangeDir(TMP_DIR, "test"), { recursive: true });
     const planPrompt = await assemblePlanPrompt(config, TMP_DIR, "test", "spec");
     expect(planPrompt).toContain("spec");
-    expect(planPrompt).toContain("test 规格");
+    expect(planPrompt).toContain("规格文档");
     expect(planPrompt).not.toContain("design");
 
     expect(config.stages.build).toBeDefined();