Update version to 3.1.0-beta for pre-release status

Changes all version references from 3.1.0 to 3.1.0-beta across:
- Main scripts (hops, install, uninstall, setup, etc.)
- Library modules (lib/*.sh)
- Documentation (README.md)

This reflects the pre-release status of the project before public release.

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

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

lib/secrets.sh

@@ -2,7 +2,7 @@
 
 # HOPS - Secret Management System
 # Secure encryption and management of sensitive configuration data
-# Version: 3.1.0
+# Version: 3.1.0-beta
 
 # Source common functions
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -190,7 +190,7 @@ create_encrypted_environment() {
     cat > "$temp_env_file" << EOF
 # HOPS Environment Configuration
 # Generated on: $(date)
-# Version: 3.1.0
+# Version: 3.1.0-beta
 
 # Core Configuration
 PUID=$puid