Replace competitor discount with price_uplift; stock pricelist detail UI

- Drop `expected_discount_pct`, add `price_uplift DECIMAL(8,4) DEFAULT 1.3`
  to `qt_competitors` (migration 040); formula: effective_price = price / uplift
- Extend `LoadLotMetrics` to return per-PN qty map (`pnQtysByLot`)
- Add virtual fields `CompetitorNames`, `PriceSpreadPct`, `PartnumberQtys`
  to `PricelistItem`; populate via `enrichWarehouseItems` / `enrichCompetitorItems`
- Competitor quotes filtered to qty > 0 before lot resolution
- New "stock layout" on pricelist detail page for warehouse/competitor:
  Partnumbers column (PN + qty, only qty>0), Поставщик column, no Настройки/Доступно
- Spread badge ±N% shown next to price for competitor rows
- Bible updated: pricelist.md, history.md

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

migrations/040_competitor_uplift.sql

@@ -0,0 +1,8 @@
+-- Replace expected_discount_pct with price_uplift.
+-- price_uplift is a divisor applied to the competitor's price to get the ex-VAT price:
+--   effective_price = price / price_uplift
+-- Default 1.3 represents a typical VAT+margin uplift.
+ALTER TABLE qt_competitors
+    ADD COLUMN price_uplift DECIMAL(8,4) NOT NULL DEFAULT 1.3000
+        COMMENT 'Price divisor: effective_price = price / price_uplift. Default 1.3.',
+    DROP COLUMN expected_discount_pct;