Settings > System: OS/journal log tab surfaces raw “[Errno 2] … ‘journalctl'” python error

FIX 2026-09-06 (code landed, unverified on live): system_ops.tail_log() no longer returns the raw subprocess error as ‘lines’ on failure (lines=[] instead); a 127/124 exit folds a clean sentence into ‘hint’ (‘journalctl is not installed on this host…’). SystemDiagnosticsCard shows a ‘Log unavailable here’ chip + hint and a plain ‘— this log source is not available in this environment —’ placeholder in the pre. — ORIGINAL: OS/journal log tab surfaced a raw “[Errno 2] No such file or directory: ‘journalctl'” string.