STATUSLINE_RE sub-1k parse records 743 tokens as 743k and would fire a /compact on a near-empty agent

Found by bin-venus-cc while fixing OPS-226, deliberately NOT fixed there because the fix is different in kind. is_idle()'s footer matcher and STATUSLINE_RE both missed 'ctx 0% (0/250k)' because fmt_k() in statusline-elazar.sh prints the k suffix only above 1000 tokens. The footer matcher was fixed by anchoring on the slash, which is safe there because that regex only decides match-or-not. STATUSLINE_RE is different: its capture group is CONSUMED AS THOUSANDS by the caller, so admitting a bare '743' with a permissive 'k?' records 743k against a 250k window - instantly above every hard tier - and arms a /compact on an agent that has barely any context. It needs a unit-aware parse (branch on whether the k suffix is present, multiply only when it is), not a loosened pattern. File: /home/rob/.local/bin/monitor-context/scan-context.py, STATUSLINE_RE. Warned in-file by bin-venus-cc. Acceptance: a captured pane fixture showing 'ctx 0% (0/250k)' and one showing 'ctx 0% (743/250k)' both parse to sub-1k values, and the actuator does not arm on either; plus the existing 'ctx 70% (176k/250k)' and legacy 'ctx 182k / 250k' shapes still parse unchanged.