refactor: remove duplicate Server methods and clean up main.go

- Removed all duplicate Server methods from main.go (630 lines)
- Fixed import conflicts and unused imports
- main.go reduced from 3,298 to 340 lines (89% reduction)
- Clean modular structure with server package handling all server functionality
- Achieved clean build with no compilation errors

🤖 Generated with [Claude Code](https://claude.ai/code)

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

cluster/sync.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"math/rand"
 	"net/http"
-	"sort"
 	"sync"
 	"time"