feat: add LOT creation, auto-save mappings, disable auto warehouse pricelist

- Add LOT creation functionality in pricing admin
  - New API endpoint POST /api/admin/pricing/lots
  - Modal form for creating new LOT with auto-category detection
  - Creates entries in both lot and qt_lot_metadata tables

- Implement auto-save for stock mappings
  - Auto-save on change for partnumber → LOT mappings
  - Visual feedback (orange during save, green on success, red on error)
  - Works in both main mappings table and import suggestions

- Improve stock import suggestions UI
  - Remove "Причина" column from suggestions table
  - Increase LOT and Partnumber column widths to 33% each
  - Better visual balance in the table layout

- Disable automatic warehouse pricelist creation on stock_log import
  - Import now completes at 100% after stock_log update
  - Manual pricelist creation available via UI when needed
  - Faster import process without auto-generation overhead

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

internal/models/user.go

@@ -16,6 +16,7 @@ type User struct {
 	Username     string    `gorm:"size:100;uniqueIndex;not null" json:"username"`
 	Email        string    `gorm:"size:255;uniqueIndex;not null" json:"email"`
 	PasswordHash string    `gorm:"size:255;not null" json:"-"`
+	// Kept for backward-compatible schema; local mode does not enforce role-based app auth.
 	Role         UserRole  `gorm:"type:enum('viewer','editor','pricing_admin','admin');default:'viewer'" json:"role"`
 	IsActive     bool      `gorm:"default:true" json:"is_active"`
 	CreatedAt    time.Time `gorm:"autoCreateTime" json:"created_at"`
@@ -25,15 +26,3 @@ type User struct {
 func (User) TableName() string {
 	return "qt_users"
 }
-
-func (u *User) CanEdit() bool {
-	return u.Role == RoleEditor || u.Role == RolePricingAdmin || u.Role == RoleAdmin
-}
-
-func (u *User) CanManagePricing() bool {
-	return u.Role == RolePricingAdmin || u.Role == RoleAdmin
-}
-
-func (u *User) CanManageUsers() bool {
-	return u.Role == RoleAdmin
-}