feat(routing): 引入多执行池智能调度

将 Worker 发现、路由画像、容量与执行传输抽象为平台无关接口，新增 Kubernetes 和静态容量适配器，并以 shadow 模式接入生产配置。

实现网络与容量评分、路由防抖、池队列、同步 Worker 租约、一次性执行令牌，以及提交状态不明时禁止重复分配的安全语义。

新增 0105 兼容迁移、管理接口、指标、OpenAPI 和回归测试。已执行全量 Go 测试、go vet、OpenAPI、迁移安全、Compose 与 Kustomize 验证。

apps/api/internal/runner/river_execution_broker.go

@@ -0,0 +1,99 @@
+package runner
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"github.com/easyai/easyai-ai-gateway/apps/api/internal/executionpool"
+	"github.com/jackc/pgx/v5"
+	"github.com/riverqueue/river"
+	"github.com/riverqueue/river/rivertype"
+)
+
+// riverExecutionBroker is the River adapter for the platform-neutral broker
+// port. Queue names and River uniqueness semantics do not escape this adapter.
+type riverExecutionBroker struct {
+	service *Service
+}
+
+func (broker riverExecutionBroker) Publish(
+	ctx context.Context,
+	poolID string,
+	taskID string,
+	notBefore time.Time,
+) (int64, error) {
+	tx, err := broker.service.store.Pool().Begin(ctx)
+	if err != nil {
+		return 0, err
+	}
+	defer func() {
+		rollbackCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		_ = tx.Rollback(rollbackCtx)
+	}()
+	jobID, err := broker.publishTx(ctx, tx, poolID, taskID, notBefore, 2)
+	if err != nil {
+		return 0, err
+	}
+	if err := tx.Commit(ctx); err != nil {
+		return 0, err
+	}
+	return jobID, nil
+}
+
+func (broker riverExecutionBroker) publishTx(
+	ctx context.Context,
+	tx pgx.Tx,
+	poolID string,
+	taskID string,
+	notBefore time.Time,
+	priority int,
+) (int64, error) {
+	riverClient := broker.service.asyncControlClient()
+	if riverClient == nil {
+		return 0, errors.New("River execution broker is not started")
+	}
+	opts := riverExecutionInsertOptions(poolID, notBefore, priority)
+	result, err := riverClient.InsertTx(ctx, tx, asyncTaskArgs{TaskID: taskID}, opts)
+	if err != nil {
+		return 0, err
+	}
+	if result.Job == nil {
+		return 0, nil
+	}
+	if _, err := tx.Exec(ctx, `
+UPDATE gateway_tasks
+SET river_job_id = $2,
+    updated_at = now()
+WHERE id = $1::uuid`, taskID, result.Job.ID); err != nil {
+		return 0, err
+	}
+	return result.Job.ID, nil
+}
+
+func riverExecutionInsertOptions(poolID string, notBefore time.Time, priority int) *river.InsertOpts {
+	if priority < 1 {
+		priority = 2
+	}
+	opts := &river.InsertOpts{
+		MaxAttempts: 1000,
+		Priority:    priority,
+		Queue:       executionpool.QueueName(poolID),
+		Tags:        []string{"gateway-task"},
+		UniqueOpts: river.UniqueOpts{
+			ByArgs: true, ByQueue: true,
+			ByState: []rivertype.JobState{
+				rivertype.JobStateAvailable, rivertype.JobStatePending,
+				rivertype.JobStateRetryable, rivertype.JobStateRunning,
+				rivertype.JobStateScheduled,
+			},
+		},
+	}
+	if !notBefore.IsZero() {
+		opts.ScheduledAt = notBefore
+	}
+	return opts
+}
+
+var _ executionpool.ExecutionBroker = riverExecutionBroker{}