feat(h5-session): Session Broker、run SSE replay 与 Finish 竞态修复

落地 H5 Session 架构 Patch 1–5（Broker 收口、Router decision、SSE taxonomy、goosed 边界检查），
并新增可选 MEMIND_RUN_STREAM_REPLAY run 事件回放与 H5 假交付 guard；修复 Finish 先于 agent-run
gate 导致 UI 永久 loading 的竞态，接入 verify:h5-session-patches 回归脚本。

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

schema.sql

@@ -357,6 +357,8 @@ CREATE TABLE IF NOT EXISTS h5_user_path_grants (
 CREATE TABLE IF NOT EXISTS h5_user_sessions (
   agent_session_id VARCHAR(128) NOT NULL PRIMARY KEY,
   user_id CHAR(36) NOT NULL,
+  goosed_node TINYINT UNSIGNED NOT NULL DEFAULT 0,
+  goosed_target VARCHAR(255) NULL,
   origin ENUM('h5', 'wechat') NOT NULL DEFAULT 'h5',
   created_at BIGINT NOT NULL,
   KEY idx_h5_user_sessions_user (user_id),