feat: add priority demotion controls

apps/web/src/pages/admin/RuntimePoliciesPanel.tsx

@@ -50,7 +50,6 @@ type RunnerPolicyForm = {
   hardStopStatusCodes: string[];
   hardStopKeywords: string[];
   priorityDemoteEnabled: boolean;
-  priorityDemoteStep: string;
   priorityDemoteCategories: string[];
   priorityDemoteCodes: string[];
   priorityDemoteStatusCodes: string[];
@@ -406,11 +405,7 @@ function RunnerPolicyEditor(props: {
               {activeStrategy === 'priorityDemote' && (
                 <div className="runtimePolicyRows runnerPolicyDetailRows">
                   <Toggle checked={props.form.priorityDemoteEnabled} label="启用优先级降级" onChange={(checked) => patch({ priorityDemoteEnabled: checked })} />
-                  <Label>
-                    降级步长
-                    <Input value={props.form.priorityDemoteStep} inputMode="numeric" onChange={(event) => patch({ priorityDemoteStep: event.target.value })} />
-                    <span className="runtimeFieldHint">命中降级规则后，失败平台动态优先级向后调整的幅度，默认 100。</span>
-                  </Label>
+                  <span className="runtimeFieldHint spanTwo">命中降级规则后，失败平台会自动调整到当前所有平台的优先级队尾。</span>
                   <KeywordField label="降级分类" value={props.form.priorityDemoteCategories} onChange={(value) => patch({ priorityDemoteCategories: value })} />
                   <KeywordField label="降级错误码" value={props.form.priorityDemoteCodes} onChange={(value) => patch({ priorityDemoteCodes: value })} />
                   <KeywordField label="降级状态码" value={props.form.priorityDemoteStatusCodes} onChange={(value) => patch({ priorityDemoteStatusCodes: value })} />
@@ -478,7 +473,6 @@ function runnerPolicyToForm(policy: GatewayRunnerPolicy | null): RunnerPolicyFor
     hardStopStatusCodes: tagsFromValue(hardStop.statusCodes ?? []),
     hardStopKeywords: tagsFromValue(hardStop.keywords ?? ['invalid_parameter', 'missing required', 'bad request', 'insufficient balance']),
     priorityDemoteEnabled: readBool(priorityDemote.enabled, true),
-    priorityDemoteStep: String(readNumber(priorityDemote.demoteStep, 100)),
     priorityDemoteCategories: tagsFromValue(priorityDemote.categories ?? ['network', 'timeout', 'stream_error', 'rate_limit', 'provider_5xx', 'provider_overloaded']),
     priorityDemoteCodes: tagsFromValue(priorityDemote.codes ?? ['network', 'timeout', 'stream_read_error', 'rate_limit', 'server_error', 'overloaded']),
     priorityDemoteStatusCodes: tagsFromValue(priorityDemote.statusCodes ?? [408, 429, 500, 502, 503, 504]),
@@ -516,7 +510,6 @@ function runnerFormToPayload(form: RunnerPolicyForm): GatewayRunnerPolicyUpsertR
     },
     priorityDemotePolicy: {
       enabled: form.priorityDemoteEnabled,
-      demoteStep: positiveInt(form.priorityDemoteStep, 100),
       categories: cleanTags(form.priorityDemoteCategories),
       codes: cleanTags(form.priorityDemoteCodes),
       statusCodes: parseNumberTags(form.priorityDemoteStatusCodes),