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>

scripts/verify-mindspace-publish-guards.mjs

@@ -18,6 +18,7 @@ function run(label, args) {
 run('MindSpace publish + chat finish unit tests', [
   '--test',
   'mindspace-public-finish-sync.test.mjs',
+  'mindspace-h5-html-finish-guard.test.mjs',
   'conversation-display.test.mjs',
   'chat-finish-sync.test.mjs',
 ]);