Teach task-finish to recycle submodule-bearing worktrees

Why: git refuses to remove a worktree with initialized submodules; the first
real dogfood run of task-finish hit this on the empty-list fix task.
Evidence: the fix task's worktree recycled only after manual force-remove;
deinit-then-remove path exercised on the same state afterwards.
Impact: finish deinitializes submodules, removes, prunes, and deletes the
remote branch; unmerged-result guard unchanged.
Refs: .task/fix-empty-list-json.md

scripts/task.sh

@@ -126,9 +126,12 @@ cmd_finish() {
     git merge-base --is-ancestor "$head" "origin/${TARGET_BRANCH}" || die "分支未合入 origin/${TARGET_BRANCH}——先走 PR 合入；放弃则用 --abandon <reason>"
     echo "[verified] ${branch} 已包含于 origin/${TARGET_BRANCH}；成果已落盘"
   fi
-  git -C "$mainrepo" worktree remove "$PWD" && git -C "$mainrepo" branch -d "$branch" 2>/dev/null || git -C "$mainrepo" branch -D "$branch"
+  git submodule deinit --all -f >/dev/null 2>&1 || true
+  git -C "$mainrepo" worktree remove "$PWD" 2>/dev/null || { echo "finish: worktree remove 失败（含未清理内容）——已验证合入，可手动 rm -rf 后 git worktree prune" >&2; exit 1; }
+  git -C "$mainrepo" branch -d "$branch" 2>/dev/null || git -C "$mainrepo" branch -D "$branch"
   git -C "$mainrepo" worktree prune
-  echo "[recycled] worktree 与分支 ${branch} 已回收（$(date -u +%FT%TZ)）"
+  git push -q --delete origin "$branch" 2>/dev/null || true
+  echo "[recycled] worktree 与分支 ${branch} 已回收（本地+远端，$(date -u +%FT%TZ)）"
 }
 
 case "${1:-}" in