Add partnumber book snapshots for QuoteForge integration

- Migrations 026-028: qt_partnumber_books + qt_partnumber_book_items
  tables; is_primary_pn on lot_partnumbers; version VARCHAR(30);
  description VARCHAR(10000) on items (required by QuoteForge sync)
- Service: CreateSnapshot expands bundles, filters empty lot_name and
  ignored PNs, copies description, activates new book atomically,
  applies GFS retention (7d/5w/12m/10y) with explicit item deletion
- Task type TaskTypePartnumberBookCreate; handlers ListPartnumberBooks
  and CreatePartnumberBook; routes GET/POST /api/admin/pricing/partnumber-books
- UI: snapshot list + "Создать снапшот сопоставлений" button with
  progress polling on /vendor-mappings page
- Bible: history, api, background-tasks, vendor-mapping updated

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

migrations/026_add_partnumber_books.sql

@@ -0,0 +1,32 @@
+-- Partnumber book snapshots for QuoteForge integration.
+-- PriceForge writes, QuoteForge reads (SELECT only).
+
+-- Add is_primary_pn to lot_partnumbers: marks which PN drives qty in vendor BOM.
+ALTER TABLE lot_partnumbers
+    ADD COLUMN IF NOT EXISTS is_primary_pn TINYINT(1) NOT NULL DEFAULT 1 AFTER lot_name;
+
+-- Versioned snapshot headers.
+CREATE TABLE IF NOT EXISTS qt_partnumber_books (
+    id         BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+    version    VARCHAR(30)  NOT NULL,
+    created_at TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    created_by VARCHAR(100) NOT NULL DEFAULT '',
+    is_active  TINYINT(1)   NOT NULL DEFAULT 0,
+    UNIQUE KEY uq_qt_partnumber_books_version (version),
+    INDEX idx_qt_partnumber_books_is_active (is_active),
+    INDEX idx_qt_partnumber_books_created_at (created_at)
+);
+
+-- Mapping rows for each snapshot.
+-- Bundles are expanded: one partnumber may produce multiple rows (one per LOT component).
+CREATE TABLE IF NOT EXISTS qt_partnumber_book_items (
+    id            BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+    book_id       BIGINT UNSIGNED NOT NULL,
+    partnumber    VARCHAR(255)    NOT NULL,
+    lot_name      VARCHAR(255)    NOT NULL,
+    is_primary_pn TINYINT(1)      NOT NULL DEFAULT 1,
+    INDEX idx_qt_partnumber_book_items_book_id (book_id),
+    INDEX idx_qt_partnumber_book_items_partnumber (partnumber),
+    CONSTRAINT fk_qt_partnumber_book_items_book
+        FOREIGN KEY (book_id) REFERENCES qt_partnumber_books (id) ON DELETE CASCADE
+);