feat(acceptance): 增加生产同构媒体压力验收模式

引入动态流量门禁、隔离验收身份与协议级 Gemini/Volces 模拟器，覆盖双站点 API、Worker、PostgreSQL、River、账务、回调和媒体物化链路。

新增 P24/P28/P32 容量阶梯、Worker 强杀恢复、真实小流量 canary、CAS 放量和失败保持 validation 的生产编排；Worker 执行槽、连接池、媒体并发和双站点副本数改为环境配置。

验证：Go 全量测试、真实 PostgreSQL 迁移集成测试、迁移安全检查、OpenAPI 生成、ShellCheck、Kustomize、gofmt 和 git diff --check。

apps/api/internal/acceptanceworkload/profiles_test.go

@@ -0,0 +1,23 @@
+package acceptanceworkload
+
+import "testing"
+
+func TestGeminiProfilesAndVideoDistribution(t *testing.T) {
+	for _, profile := range []GeminiProfile{GeminiBaseline, GeminiLarge, GeminiPeak} {
+		resolved, ok := GeminiProfileByName(profile.Name)
+		if !ok || resolved != profile {
+			t.Fatalf("profile %q resolved to %+v, ok=%v", profile.Name, resolved, ok)
+		}
+		if profile.Requests <= 0 || profile.InputBytes <= 0 || profile.OutputBytes <= 0 ||
+			profile.DelayMin <= 0 || profile.DelayMax < profile.DelayMin {
+			t.Fatalf("invalid Gemini profile: %+v", profile)
+		}
+	}
+	counts := map[int]int{}
+	for index := 0; index < 100; index++ {
+		counts[VideoImageCount(index)]++
+	}
+	if counts[3] != 60 || counts[6] != 30 || counts[9] != 10 {
+		t.Fatalf("video image distribution=%v", counts)
+	}
+}