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.go

@@ -5,7 +5,6 @@ import (
 	"net/url"
 	"strings"
 	"sync"
-	"time"
 
 	"github.com/easyai/easyai-ai-gateway/apps/api/internal/clients"
 	"github.com/easyai/easyai-ai-gateway/apps/api/internal/netproxy"
@@ -19,8 +18,6 @@ type httpClientCache struct {
 	custom map[string]*http.Client
 }
 
-const providerHTTPClientTimeout = 10 * time.Minute
-
 const (
 	providerHTTPMaxIdleConnections        = 2048
 	providerHTTPMaxIdleConnectionsPerHost = 1024
@@ -34,16 +31,19 @@ func newHTTPClientCache() *httpClientCache {
 	}
 }
 
-func (s *Service) httpClientForCandidate(candidate store.RuntimeModelCandidate, simulated bool) (*http.Client, error) {
+func (s *Service) httpClientForCandidate(candidate store.RuntimeModelCandidate, simulated bool, kind string) (*http.Client, error) {
+	var client *http.Client
 	if simulated {
-		return s.httpClients.none, nil
+		client = s.httpClients.none
+		return providerHTTPClientForKind(client, kind), nil
 	}
 	// Some Worker sites have direct provider egress but are not authorized to
 	// use a platform's shared proxy. Keep this override explicitly scoped to
 	// platform UUIDs so one site's routing exception cannot bypass proxies for
 	// unrelated providers or platforms.
 	if platformIDListed(s.cfg.PlatformProxyBypassIDs, candidate.PlatformID) {
-		return s.httpClients.none, nil
+		client = s.httpClients.none
+		return providerHTTPClientForKind(client, kind), nil
 	}
 	config, err := netproxy.Normalize(netproxy.FromPlatformConfig(candidate.PlatformConfig))
 	if err != nil {
@@ -52,14 +52,22 @@ func (s *Service) httpClientForCandidate(candidate store.RuntimeModelCandidate,
 	switch config.Mode {
 	case netproxy.ModeGlobal:
 		if strings.TrimSpace(s.cfg.GlobalHTTPProxy) != "" {
-			return s.httpClients.customClient(s.cfg.GlobalHTTPProxy)
+			client, err = s.httpClients.customClient(s.cfg.GlobalHTTPProxy)
+			if err != nil {
+				return nil, err
+			}
+			break
 		}
-		return s.httpClients.global, nil
+		client = s.httpClients.global
 	case netproxy.ModeCustom:
-		return s.httpClients.customClient(config.HTTPProxy)
+		client, err = s.httpClients.customClient(config.HTTPProxy)
+		if err != nil {
+			return nil, err
+		}
 	default:
-		return s.httpClients.none, nil
+		client = s.httpClients.none
 	}
+	return providerHTTPClientForKind(client, kind), nil
 }
 
 func platformIDListed(raw string, platformID string) bool {
@@ -100,7 +108,16 @@ func newHTTPClient(proxy func(*http.Request) (*url.URL, error)) *http.Client {
 	transport.MaxIdleConns = providerHTTPMaxIdleConnections
 	transport.MaxIdleConnsPerHost = providerHTTPMaxIdleConnectionsPerHost
 	return &http.Client{
-		Timeout:   providerHTTPClientTimeout,
+		Timeout:   clients.ProviderRequestTimeout(""),
 		Transport: transport,
 	}
 }
+
+func providerHTTPClientForKind(base *http.Client, kind string) *http.Client {
+	if base == nil || base.Timeout == clients.ProviderRequestTimeout(kind) {
+		return base
+	}
+	client := *base
+	client.Timeout = clients.ProviderRequestTimeout(kind)
+	return &client
+}