Stop button had no effect: run_scan only checked the cancel flag between
CIDR ranges and between hosts, never inside the per-range nmap call. For a
single /24 the whole scan is one blocking call, so cancel was ignored for
minutes and the run status stayed 'running'.
- thread run_id into _nmap_scan/_ping_sweep/_nmap_port_scan; check cancel
before each phase and skip queued hosts once cancelled
- flip ScanRun status to 'cancelled' eagerly in the stop endpoint so the UI
reacts immediately instead of waiting for a checkpoint
Fixes#218
ha-relevant: yes