perf(queue): 按策略动态扩缩异步 Worker

将 River 执行容量按平台模型与用户组的有效并发策略动态调整，并为长任务续租、并发租约原子抢占和限流退避补充保护。\n\n统一平台模型限流继承语义，兼容历史 platformLimits/modelLimits，并为三个迁移图像模型建立独立并发租约。补充管理端显式继承/覆盖配置、指标、单元测试及隔离 PostgreSQL 验收。\n\n验证：go test ./... -count=1；pnpm lint；pnpm test；pnpm build；隔离 PostgreSQL 并发原子性/续租测试；128 任务与三分钟长任务动态 Worker 验收。

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

@@ -409,13 +409,13 @@ function ModelBindingPolicy(props: { form: PlatformWizardForm; onChange: (value:
           </Label>
         </>
       )}
-      <ToggleField checked={form.modelOverrideRateLimit} label="覆盖模型限流策略" onChange={(checked) => onChange({ ...form, modelOverrideRateLimit: checked })} />
+      <ToggleField checked={form.modelOverrideRateLimit} label="覆盖模型限流策略" onChange={(checked) => onChange({ ...form, modelOverrideRateLimit: checked, modelRateLimitOverrideTouched: true })} />
       {form.modelOverrideRateLimit && (
         <>
-          <Label>模型 RPM<Input value={form.modelRpmLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelRpmLimit: event.target.value })} /></Label>
-          <Label>模型 RPS<Input value={form.modelRpsLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelRpsLimit: event.target.value })} /></Label>
-          <Label>模型 TPM<Input value={form.modelTpmLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelTpmLimit: event.target.value })} /></Label>
-          <Label>模型并发<Input value={form.modelConcurrencyLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelConcurrencyLimit: event.target.value })} /></Label>
+          <Label>模型 RPM<Input value={form.modelRpmLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelRpmLimit: event.target.value, modelRateLimitOverrideTouched: true })} /></Label>
+          <Label>模型 RPS<Input value={form.modelRpsLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelRpsLimit: event.target.value, modelRateLimitOverrideTouched: true })} /></Label>
+          <Label>模型 TPM<Input value={form.modelTpmLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelTpmLimit: event.target.value, modelRateLimitOverrideTouched: true })} /></Label>
+          <Label>模型并发<Input value={form.modelConcurrencyLimit} placeholder="不填则不限制" inputMode="numeric" onChange={(event) => onChange({ ...form, modelConcurrencyLimit: event.target.value, modelRateLimitOverrideTouched: true })} /></Label>
         </>
       )}
     </div>
@@ -1004,6 +1004,7 @@ function platformToForm(
   const rateLimitPolicy = platform.rateLimitPolicy ?? {};
   const networkProxy = readNetworkProxyConfig(config);
   const currentModels = platformModels.filter((model) => model.platformId === platform.id);
+  const modelRateLimitPolicy = currentModels.find((model) => model.rateLimitPolicyMode === 'override')?.rateLimitPolicy ?? {};
   return {
     ...createEmptyPlatformForm(platform.provider, defaults),
     provider: platform.provider,
@@ -1034,6 +1035,12 @@ function platformToForm(
     selectedModelIds: platformModelBaseIds(platform, baseModels, currentModels),
     modelDiscountFactors: platformModelDiscountFactors(platform, baseModels, currentModels),
     modelNameMappings: platformModelNameMappings(platform, baseModels, currentModels),
+    modelOverrideRateLimit: currentModels.length > 0 && currentModels.every((model) => model.rateLimitPolicyMode === 'override'),
+    modelRateLimitOverrideTouched: false,
+    modelRpmLimit: readLimit(modelRateLimitPolicy, 'rpm'),
+    modelRpsLimit: readLimit(modelRateLimitPolicy, 'rps'),
+    modelTpmLimit: readLimit(modelRateLimitPolicy, 'tpm_total'),
+    modelConcurrencyLimit: readLimit(modelRateLimitPolicy, 'concurrent'),
     selectionMode: 'partial',
   };
 }