Package-level declarations

Picks AT MOST ONE of the three ChatComponent capture mixins per runtime, so their entry points cannot overlap and no line is captured twice.

Chat capture for 1.19 - 1.21: addMessage(Component, MessageSignature, GuiMessageTag), the one entry BOTH system messages and player chat pass through — /say, /me and other players never reach the 1-arg entry, which is a pure delegate into this one.

Chat capture for <=1.18.2, where chat has no system/player split: the 1-arg entry is the only one and sees everything.

Chat capture for 26.1+, which split the one entry into three siblings — two system, one player — that each funnel into a private method.

The plugin gate: a hybrid server loads and enables its plugins inside this method, so from its RETURN a mod host's plugin classpath is finally complete.

Client + render lane heartbeats, as a mixin.

Server-lane heartbeat + the server-stop reap, as a mixin.