feat(h5): web 联网能力、实时查询路由与 session Finish 对齐

- 新增 web 能力并挂载 platform/web（web_search/fetch_url）
- 实时查询强制 web skill，router fallback 与 await session Finish
- Session Broker 覆盖率/指标、stream replay 与相关单测/E2E 脚本

Co-authored-by: Cursor <cursoragent@cursor.com>

schema.sql

@@ -395,6 +395,20 @@ CREATE TABLE IF NOT EXISTS h5_agent_run_events (
   CONSTRAINT fk_h5_agent_run_event_run FOREIGN KEY (run_id) REFERENCES h5_agent_runs(id) ON DELETE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
+-- Patch 4c session SSE replay cursor store (rollback: DROP TABLE h5_session_stream_events).
+CREATE TABLE IF NOT EXISTS h5_session_stream_events (
+  id CHAR(36) PRIMARY KEY,
+  user_id CHAR(36) NOT NULL,
+  agent_session_id VARCHAR(128) NOT NULL,
+  event_type VARCHAR(64) NOT NULL,
+  payload_json LONGTEXT NOT NULL,
+  upstream_event_id VARCHAR(255) NULL,
+  created_at BIGINT NOT NULL,
+  KEY idx_h5_session_stream_session (agent_session_id, created_at, id),
+  KEY idx_h5_session_stream_user (user_id, created_at),
+  CONSTRAINT fk_h5_session_stream_user FOREIGN KEY (user_id) REFERENCES h5_users(id) ON DELETE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
 CREATE TABLE IF NOT EXISTS h5_conversation_packages (
   id VARCHAR(64) PRIMARY KEY,
   user_id CHAR(36) NOT NULL,