Improve crawler performance and worker coordination

- Add WaitGroup synchronization for workers to prevent overlapping scheduler runs
- Increase history fetch multiplier and sleep intervals for better resource usage
- Simplify error handling and logging in worker processing
- Update SQL query to exclude error snapshots from history selection
- Fix worker ID variable reference in spawning loop
- Streamline snapshot update logic and error reporting

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

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

common/shared.go

@@ -1,6 +1,9 @@
 package common
 
-import "os"
+import (
+	"os"
+	"sync"
+)
 
 // FatalErrorsChan accepts errors from workers.
 // In case of fatal error, gracefully
@@ -8,6 +11,7 @@ import "os"
 var (
 	FatalErrorsChan chan error
 	SignalsChan     chan os.Signal
+	WorkerWG        sync.WaitGroup
 )
 
 const VERSION string = "0.0.1"