refactor: rename binary from quoteforge to qfs

- Rename cmd/server to cmd/qfs for shorter binary name
- Update all documentation references (README, CLAUDE.md, etc.)
- Update build commands to output bin/qfs
- Binary name now matches directory name

Usage:
  go run ./cmd/qfs              # Development
  go build -o bin/qfs ./cmd/qfs # Production

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

LOCAL_FIRST_INTEGRATION.md

@@ -60,7 +60,7 @@ localConfigService := services.NewLocalConfigurationService(
 ### Шаг 1: Обновить main.go
 
 ```go
-// В cmd/server/main.go
+// В cmd/qfs/main.go
 syncService := sync.NewService(pricelistRepo, configRepo, local)
 
 // Создать isOnline функцию
@@ -165,7 +165,7 @@ type PendingChange struct {
 
 ```bash
 # Compile
-go build ./cmd/server
+go build ./cmd/qfs
 
 # Run
 ./quoteforge