Stats tests set PI_CONFIG_DIR + setAgentDir(home/<config>/agent), which resolves equal to the default agent dir and routes stats.db through $XDG_DATA_HOME/omp/stats.db whenever an XDG var is set, leaking rows across tests. The shared installStatsTestIsolation helper now snapshots and clears XDG_*_HOME with PI_CONFIG_DIR on each test, points the agent dir at a fresh TempDir, closes the DB handle, and restores the prior env after the test.
Replaced the stats session parser's Bun.JSONL.parseChunk path with a lenient JS line scanner so large session files do not enter the native parser before /stats launches.
Fixes#3733