Ingest cadence fast-reading thresholds (moisture step/slope, EC slope, release, event and reinstall holds) were compile-time constants

Found 2026-09-14 (ingest-orchestrator pass left them ‘exposed under Settings › Grow › Sensors if they need tuning’). FIXED 2026-09-14 (PR #270, merged eb7d6a5, deployed): six helper tunables (input_number.dsc_cadence_*) read once per tick through ingest_cadence.tuning(); mark_active’s default hold follows the setting; GET /ingest/cadence ‘tuning’ reports the live values instead of the constants. Rendered on Settings › Sensors › Fast reading, searchable. The defaults pin test asserts registry defaults == module constants == helper_float literals. Verified live: /ingest/cadence tuning shows moisture_step_pct 15, slope 2 %/h, EC 10 %/h, release 600 s, holds 1800 s after the deploy.