Placed-sensor stale window and runoff sitting hold were bare settings keys with no settings row (climate_stale_min, runoff_sitting_min)

Found 2026-09-14 (FOLLOWUPS open items from the zone-placement pass): both thresholds could only be changed by PATCHing a raw settings key, and the Placed climate / Runoff trays cards named the key in . FIXED 2026-09-14 (PR #270, merged eb7d6a5, deployed 21:12): both are brain-held helper tunables (input_number.dsc_climate_stale_min, input_number.dsc_runoff_sitting_min) rendered by HelperTunableRows on Settings › Sensors › Placed sensors with default/range/reset/journal; the consumers read hub_tunables.helper_float() and still honour the old bare keys when the helper is unset (test pins the precedence). The two cards now link to the settings row. Verified: settings page walkthrough on the demo brain; live GET /settings/hub-tunables serves 13 helpers (groups trust / placement / cadence) with both placement rows at their 30 min defaults after the deploy.