Rename test file references: Bookmann → Bookhoard

Test file updates:
- Update import paths in test files: bookmann/internal → bookhoard/internal
- Update test helper functions and references
- Update test comments and documentation

This is part 6 of the project rename to Bookhoard.

cmd/server/tests/security_test.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	ratelimit "bookmann/internal/middleware"
+	ratelimit "bookhoard/internal/middleware"
 	"net/http"
 	"net/http/httptest"
 	"testing"