Update bible: competitors API endpoints and pricelist deletion/competitor sections

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bible-local/pricelist.md

@@ -129,3 +129,22 @@ Task type: `TaskTypePricelistCreate`.
 - Service: `internal/services/pricelist/service.go`
 - Warehouse calc: `internal/warehouse/snapshot.go`
 - Handler: `internal/handlers/pricelist.go`
+
+---
+
+## Pricelist Deletion Guard
+
+`CountUsage(id)` checks `qt_configurations` for references across **all three** pricelist columns:
+`pricelist_id`, `warehouse_pricelist_id`, `competitor_pricelist_id`.
+
+A pricelist is only deletable when all three counts are zero.
+
+---
+
+## Competitor Pricelist
+
+- **Source**: `competitor`
+- **Rebuilt via**: `POST /api/competitors/pricelist` (task type: `competitor_import`)
+- **Logic**: Latest quote per `(competitor_id, partnumber)` across ALL active competitors → apply each competitor's `expected_discount_pct` → `weighted_median` per lot → insert into `qt_pricelist_items`
+- **price_method**: `weighted_median`, **price_period_days**: `0`
+- Quotes stored in `partnumber_log_competitors`; unmapped p/ns recorded in `qt_vendor_partnumber_seen` with `source_type = 'competitor:<code>'`