feat: add NSB manager CLI for service lifecycle management

[EclipseWraith]

Summary

Added a CLI tool to manage NSB services (Redis + daemon) from a single
interface, replacing the need to manually run multiple commands across
multiple terminals.

Usage

python nsb_manager.py start   -c config.yaml   # start Redis + daemon
python nsb_manager.py stop    -c config.yaml   # stop all services
python nsb_manager.py status  -c config.yaml   # check what's running
python nsb_manager.py restart -c config.yaml   # restart everything

What it does

• Reads config.yaml to determine ports and settings
• Starts/stops Redis and nsb_daemon as a pair
• Checks for port conflicts before starting
• Auto-discovers the nsb_daemon binary in build/ or system PATH
• Reports clear status with service state, ports, and config info

Before vs After

Before (5 manual commands):
redis-server --port 5050 --daemonize yes
redis-cli -p 5050 ping
cd build && ./nsb_daemon ../config.yaml &
kill $(lsof -t -i:65432)
redis-cli -p 5050 shutdown

After (1 command):
python nsb_manager.py start -c config.yaml

Testing

Verified on WSL Ubuntu 24.04. All services start, stop, and restart
correctly. Client connectivity confirmed after manager-initiated startup.