fix(provider): 延长媒体超时并终止超时轮转

将图像和视频的默认 HTTP/轮询超时分别提高到 20 分钟和 30 分钟。媒体任务超时后直接失败，不再重试、切换客户端或标记为 upstream_submission_unknown。OpenAI 图像端点遇到上游明确拒绝 response_format 时自动移除并缓存兼容结论。

验证：go test ./... -count=1；go vet ./...；gofmt；相关 Shell bash -n、ShellCheck 与发布脚本回归测试。

apps/api/internal/runner/proxy_test.go

@@ -16,6 +16,19 @@ func TestProviderHTTPClientTimeoutAllowsLongRunningMediaRequests(t *testing.T) {
 	if client.Timeout != 10*time.Minute {
 		t.Fatalf("unexpected provider HTTP timeout: got %s want %s", client.Timeout, 10*time.Minute)
 	}
+	for _, test := range []struct {
+		kind string
+		want time.Duration
+	}{
+		{kind: "images.generations", want: 20 * time.Minute},
+		{kind: "images.edits", want: 20 * time.Minute},
+		{kind: "videos.generations", want: 30 * time.Minute},
+		{kind: "chat.completions", want: 10 * time.Minute},
+	} {
+		if got := providerHTTPClientForKind(client, test.kind).Timeout; got != test.want {
+			t.Fatalf("provider HTTP timeout for %s: got %s want %s", test.kind, got, test.want)
+		}
+	}
 	transport, ok := client.Transport.(*http.Transport)
 	if !ok {
 		t.Fatalf("provider transport type = %T, want *http.Transport", client.Transport)
@@ -51,7 +64,7 @@ func TestPlatformProxyModeNoneIgnoresEnvironmentProxy(t *testing.T) {
 
 	client, err := testProxyService(config.Config{}).httpClientForCandidate(store.RuntimeModelCandidate{
 		PlatformConfig: map[string]any{"networkProxy": map[string]any{"mode": "none"}},
-	}, false)
+	}, false, "chat.completions")
 	if err != nil {
 		t.Fatalf("build http client: %v", err)
 	}
@@ -86,7 +99,7 @@ func TestPlatformProxyModeCustomUsesConfiguredHTTPProxy(t *testing.T) {
 
 	client, err := testProxyService(config.Config{}).httpClientForCandidate(store.RuntimeModelCandidate{
 		PlatformConfig: map[string]any{"networkProxy": map[string]any{"mode": "custom", "httpProxy": proxy.URL}},
-	}, false)
+	}, false, "chat.completions")
 	if err != nil {
 		t.Fatalf("build http client: %v", err)
 	}
@@ -121,7 +134,7 @@ func TestPlatformProxyBypassIDUsesDirectConnection(t *testing.T) {
 	}).httpClientForCandidate(store.RuntimeModelCandidate{
 		PlatformID:     "official-gemini-platform",
 		PlatformConfig: map[string]any{"networkProxy": map[string]any{"mode": "custom", "httpProxy": proxy.URL}},
-	}, false)
+	}, false, "chat.completions")
 	if err != nil {
 		t.Fatalf("build bypassed http client: %v", err)
 	}
@@ -153,7 +166,7 @@ func TestPlatformProxyModeGlobalUsesConfiguredGlobalHTTPProxy(t *testing.T) {
 
 	client, err := testProxyService(config.Config{GlobalHTTPProxy: proxy.URL}).httpClientForCandidate(store.RuntimeModelCandidate{
 		PlatformConfig: map[string]any{"networkProxy": map[string]any{"mode": "global"}},
-	}, false)
+	}, false, "chat.completions")
 	if err != nil {
 		t.Fatalf("build http client: %v", err)
 	}