Add hide component feature, usage indicators, and Docker support

- Add is_hidden field to hide components from configurator
- Add colored dot indicator showing component usage status:
  - Green: available in configurator
  - Cyan: used as source for meta-articles
  - Gray: hidden from configurator
- Optimize price recalculation with caching and skip unchanged
- Show current lot name during price recalculation
- Add Dockerfile (Alpine-based multi-stage build)
- Add docker-compose.yml and .dockerignore

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

internal/models/metadata.go

@@ -51,6 +51,7 @@ type LotMetadata struct {
 	MetaPrices       string       `gorm:"size:1000" json:"meta_prices"`
 	MetaMethod       string       `gorm:"size:20" json:"meta_method"`
 	MetaPeriodDays   int          `gorm:"default:90" json:"meta_period_days"`
+	IsHidden         bool         `gorm:"default:false" json:"is_hidden"`
 
 	// Relations
 	Lot      *Lot      `gorm:"foreignKey:LotName;references:LotName" json:"lot,omitempty"`