fix: prevent thread pool leaks in searcher (#1273)#1308

CaralHsi wants to merge 1 commit intoMemTensor:dev-20260323-v2.0.11MemTensor/MemOS:dev-20260323-v2.0.11from

CaralHsi:fix-1273-searcher-thread-leakCaralHsi/MemOS:fix-1273-searcher-thread-leakCopy head branch name to clipboard