feat(acceptance): 建立同构验收与弹性容量体系

实现本地三节点 K3s 同构环境、脱敏生产快照、Gemini 图片和多参考图视频协议模拟、统一验收报告及故障注入。\n\n新增 Worker 容量控制器、资源与连接预算、任务恢复保护，并将生产验收拆分为 validation 执行和人工 CAS 放量。\n\n验证包括 Go 全量测试、PostgreSQL HTTP 集成测试、go vet、OpenAPI、ShellCheck、前端检查、迁移及发布脚本测试。

apps/api/migrations/0096_worker_capacity_controller.sql

@@ -0,0 +1,39 @@
+ALTER TABLE gateway_worker_instances
+  DROP CONSTRAINT gateway_worker_instances_status_check,
+  ADD COLUMN draining_at timestamptz,
+  ADD CONSTRAINT gateway_worker_instances_status_check
+    CHECK (status IN ('active', 'draining', 'stale'));
+
+CREATE TABLE gateway_capacity_profiles (
+  profile_key text PRIMARY KEY,
+  release_sha text NOT NULL,
+  config_hash text NOT NULL,
+  acceptance_run_id uuid REFERENCES gateway_acceptance_runs(id) ON DELETE RESTRICT,
+  kind text NOT NULL,
+  model text NOT NULL DEFAULT '*',
+  capacity_profile text NOT NULL,
+  stable_throughput_per_second numeric(18, 6) NOT NULL,
+  admitted_throughput_per_second numeric(18, 6) NOT NULL,
+  max_running integer NOT NULL,
+  max_queued integer NOT NULL,
+  max_predicted_wait_seconds integer NOT NULL,
+  enabled boolean NOT NULL DEFAULT false,
+  metadata jsonb NOT NULL DEFAULT '{}'::jsonb,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  updated_at timestamptz NOT NULL DEFAULT now(),
+  CONSTRAINT gateway_capacity_profiles_kind_check
+    CHECK (kind IN ('image', 'video', 'mixed')),
+  CONSTRAINT gateway_capacity_profiles_values_check
+    CHECK (
+      stable_throughput_per_second > 0
+      AND admitted_throughput_per_second > 0
+      AND admitted_throughput_per_second <= stable_throughput_per_second
+      AND max_running > 0
+      AND max_queued >= 0
+      AND max_predicted_wait_seconds > 0
+    )
+);
+
+CREATE UNIQUE INDEX uniq_gateway_capacity_profiles_enabled_kind_model
+  ON gateway_capacity_profiles (kind, model)
+  WHERE enabled = true;

apps/api/migrations/0097_worker_runtime_owner_index.sql

@@ -0,0 +1,5 @@
+-- easyai:migration:no-transaction
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_gateway_tasks_runtime_owner
+  ON gateway_tasks (locked_by, execution_lease_expires_at, id)
+  WHERE status IN ('queued', 'running')
+    AND execution_lease_expires_at IS NOT NULL;