Trigger Meta
class TriggerMeta(val id: Int, var type: String, val module: TesseraModule?, val callback: TesseraCallback)
One registered trigger. The callback (an arrow function, or a named function via convention) is stored as a uniform TesseraCallback, so the engine invokes bytecode lambdas and GraalJS guest functions the same way. module is nullable (null for /te eval snippets) and is only used to unload a module's hooks.