feat: production-grade hardening v1.1.0

- fix: Compile() defensive map copy, prevents post-compile Graph mutation
- fix: correct 'origin'→'destination' in edge validation error message
- feat: export ErrNotPaused/ErrAlreadyFinished for errors.Is() support
- feat: WithPreNodeHook/WithPostNodeHook now support chaining (multiple hooks)
- feat: Compile detects conflicting outgoing edge types on same node
- fix: FileCheckpointer atomic write (tmp+rename, crash-safe)
- fix: FileCheckpointer threadID path traversal validation
- refactor: remove redundant continue in run() loop
- docs: add doc.go package-level documentation
- test: +7 test cases covering error paths, edge conflicts, hook chaining

examples/hooks/main.go

@@ -6,7 +6,7 @@ import (
 	"log"
 	"time"
 
-	GopherGraph "github.com/unclesam-LY/GopherGraph"
+	GopherGraph "github.com/unclesam-ly/GopherGraph"
 )
 
 // AgentState 是这个示例工作流的状态