Rename project documentation: Bookmann → Bookhoard

Documentation updates:
- Update README.md title and all references
- Update PROJECT_GUIDELINES.md title and guidelines
- Update all documentation files in docs/ directory
- Update device setup guides (Kobo, KOReader)
- Update API and architecture documentation
- Update completion summaries and progress reports

This is part 5 of the project rename to Bookhoard.

docs/SECURITY_AUDIT.md

@@ -1,9 +1,9 @@
-# Bookmann Security Audit Report
+# Bookhoard Security Audit Report
 ## Universal Sync Implementation (Phases 1-7)
 
 **Date**: January 31, 2026
 **Version**: 1.0.0
-**Auditor**: Bookmann Security Team
+**Auditor**: Bookhoard Security Team
 
 ---
 
@@ -513,6 +513,6 @@ Audit Logs: 180 days
 
 ---
 
-**Audit Completed By**: Bookmann Security Team  
+**Audit Completed By**: Bookhoard Security Team  
 **Next Audit**: Within 3 months of production deployment  
 **Questions**: security@bookmann.example.com