Unified Quote Journal (parts_log) v3

- New unified append-only quote log table parts_log replaces three
  separate log tables (stock_log, partnumber_log_competitors, lot_log)
- Migrations 042-049: extend supplier, create parts_log/import_formats/
  ignore_rules, rework qt_lot_metadata composite PK, add lead_time_weeks
  to pricelist_items, backfill data, migrate ignore rules
- New services: PartsLogBackfillService, ImportFormatService,
  UnifiedImportService; new world pricelist type (all supplier types)
- qt_lot_metadata PK changed to (lot_name, pricelist_type); all queries
  now filter WHERE pricelist_type='estimate'
- Fix pre-existing bug: qt_component_usage_stats column names
  quotes_last30d/quotes_last7d (no underscore) — added explicit gorm tags
- Bible: full table inventory, baseline schema snapshot, updated pricelist/
  data-rules/api/history/architecture docs

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

migrations/044_create_import_formats.sql

@@ -0,0 +1,26 @@
+-- Import formats table: stores file format definitions for unified import.
+-- Column mapping JSON uses same structure as qt_competitors.column_mapping.
+CREATE TABLE IF NOT EXISTS qt_import_formats (
+    format_code     VARCHAR(100) NOT NULL PRIMARY KEY
+        COMMENT 'Symbolic code: treolan_b2b, s4b_export, ocs_sklad, json_connector',
+    name            VARCHAR(255) NOT NULL,
+    file_type       ENUM('csv','xlsx','mxl','json') NOT NULL,
+    header_row      INT NOT NULL DEFAULT 1,
+    data_start_row  INT NOT NULL DEFAULT 2,
+    delimiter       VARCHAR(5) NULL
+        COMMENT 'For CSV only',
+    encoding        VARCHAR(20) NOT NULL DEFAULT 'utf-8',
+    column_mapping  JSON NULL
+        COMMENT 'Column mapping — same format as qt_competitors.column_mapping',
+    sample_filename VARCHAR(500) NULL,
+    notes           TEXT NULL,
+    is_active       TINYINT(1) NOT NULL DEFAULT 1,
+    created_at      TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at      TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+-- Add FK from supplier to import formats (deferred until qt_import_formats exists)
+ALTER TABLE supplier
+    ADD CONSTRAINT fk_supplier_import_format
+        FOREIGN KEY (default_import_format_code) REFERENCES qt_import_formats(format_code)
+        ON DELETE SET NULL;