Dev server: print Network URL alongside localhost

[Andrew-Velox]

zig build dev only prints http://localhost:3000. Other frameworks (Vite, Next) also show a Network URL so you can open the app from another device on the same Wi-Fi:

Local: http://localhost:3000
Network: http://192.168.x.x:3000

The dev proxy already binds to 0.0.0.0 (src/cli/dev.zig), so it's already reachable over the LAN, we just don't print the IP.

[nurulhudaapon]

@Andrew-Velox Let's actually deprioritize it for later, for now let's continue having the single line thing. Later will have to rebuild the DevServer during Zig 0.17 migration to work with the build system protocol once that is done we can improve a lot in this area.