NOTE
Netty Server Startup Overview
ServerBootstrap to active listener: channel creation, initialization, event-loop registration, and bind.
This is a historical learning note and may contain outdated or incomplete understanding.
Netty server startup has four stable conceptual phases: create channel → initialize pipeline/options → register with an event loop → bind/listen.
After activation, the parent channel accepts connections; each child is initialized and registered with a worker event loop, then its inbound/outbound events travel through its own pipeline.
This model remains useful across Netty releases even when the exact internal methods/classes change.