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/api/internal/store/platform_models.go

@@ -143,18 +143,13 @@ SELECT EXISTS (
 	// soon as the base pricing rule changes and can mask the authoritative rule.
 	billingConfig := input.BillingConfig
 	explicitRuntimePolicySetID := strings.TrimSpace(input.RuntimePolicySetID)
+	rateLimitPolicyMode := NormalizeRateLimitPolicyMode(input.RateLimitPolicyMode, input.RateLimitPolicy != nil)
 	rateLimitPolicy := input.RateLimitPolicy
-	if len(rateLimitPolicy) == 0 && explicitRuntimePolicySetID == "" {
-		rateLimitPolicy = base.DefaultRateLimitPolicy
+	if rateLimitPolicyMode == RateLimitPolicyModeInherit {
+		rateLimitPolicy = nil
 	}
 	runtimePolicySetID := explicitRuntimePolicySetID
-	if runtimePolicySetID == "" {
-		runtimePolicySetID = base.RuntimePolicySetID
-	}
 	runtimePolicyOverride := input.RuntimePolicyOverride
-	if len(runtimePolicyOverride) == 0 {
-		runtimePolicyOverride = base.RuntimePolicyOverride
-	}
 
 	capabilityOverrideJSON, _ := json.Marshal(emptyObjectIfNil(input.CapabilityOverride))
 	capabilitiesJSON, _ := json.Marshal(emptyObjectIfNil(capabilities))
@@ -189,14 +184,14 @@ SELECT EXISTS (
 INSERT INTO platform_models (
   platform_id, base_model_id, model_name, provider_model_name, model_alias, model_type, display_name,
   capability_override, capabilities, pricing_mode, discount_factor,
-  pricing_rule_set_id, billing_config_override, billing_config, permission_config, retry_policy, rate_limit_policy,
+  pricing_rule_set_id, billing_config_override, billing_config, permission_config, retry_policy, rate_limit_policy, rate_limit_policy_mode,
   runtime_policy_set_id, runtime_policy_override, enabled
 )
 VALUES (
   $1::uuid, $2::uuid, $3, NULLIF($4, ''), NULLIF($5, ''), $6::jsonb, $7,
   $8::jsonb, $9::jsonb, $10, $11::numeric,
-  NULLIF($12, '')::uuid, $13::jsonb, $14::jsonb, $15::jsonb, $16::jsonb, $17::jsonb,
-  NULLIF($18, '')::uuid, $19::jsonb, true
+  NULLIF($12, '')::uuid, $13::jsonb, $14::jsonb, $15::jsonb, $16::jsonb, $17::jsonb, $18,
+  NULLIF($19, '')::uuid, $20::jsonb, true
 )
 ON CONFLICT (platform_id, model_name) DO UPDATE
 SET base_model_id = EXCLUDED.base_model_id,
@@ -213,6 +208,7 @@ SET base_model_id = EXCLUDED.base_model_id,
     permission_config = EXCLUDED.permission_config,
     retry_policy = EXCLUDED.retry_policy,
     rate_limit_policy = EXCLUDED.rate_limit_policy,
+    rate_limit_policy_mode = EXCLUDED.rate_limit_policy_mode,
     runtime_policy_set_id = EXCLUDED.runtime_policy_set_id,
     runtime_policy_override = EXCLUDED.runtime_policy_override,
     enabled = true,
@@ -221,7 +217,7 @@ RETURNING id::text, platform_id::text, COALESCE(base_model_id::text, ''), model_
           COALESCE(NULLIF(provider_model_name, ''), model_name), COALESCE(model_alias, ''), model_type, display_name, capability_override,
           capabilities, pricing_mode, COALESCE(discount_factor, 0)::float8,
           COALESCE(pricing_rule_set_id::text, ''), billing_config_override, billing_config,
-          permission_config, retry_policy, rate_limit_policy, COALESCE(runtime_policy_set_id::text, ''), runtime_policy_override,
+          permission_config, retry_policy, rate_limit_policy, rate_limit_policy_mode, COALESCE(runtime_policy_set_id::text, ''), runtime_policy_override,
           COALESCE(to_char(cooldown_until AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS.MS"Z"'), ''),
           enabled, created_at, updated_at`,
 		input.PlatformID,
@@ -241,6 +237,7 @@ RETURNING id::text, platform_id::text, COALESCE(base_model_id::text, ''), model_
 		string(permissionJSON),
 		string(retryJSON),
 		string(rateLimitJSON),
+		rateLimitPolicyMode,
 		runtimePolicySetID,
 		string(runtimePolicyOverrideJSON),
 	).Scan(
@@ -262,6 +259,7 @@ RETURNING id::text, platform_id::text, COALESCE(base_model_id::text, ''), model_
 		&permissionBytes,
 		&retryPolicyBytes,
 		&rateLimitPolicyBytes,
+		&model.RateLimitPolicyMode,
 		&model.RuntimePolicySetID,
 		&runtimePolicyOverrideBytes,
 		&model.CooldownUntil,