Support @koa/router@14 and @koa/router@15

[peterjroberts]

Is your feature request related to a problem? Please describe.

@koa/router v14.0.0 was released in Aug 2025, v15.0.0 in Dec 2025. The Elastic Node.js APM agent currently still requires <14.

While we do get the majority of instrumentation with v14 or v15, it currently does not automatically assign paths as transaction names as it does in v13

Describe the solution you'd like
Full support for v14 and v15 of @koa/router. (Potentially also under the old name koa-router for v14)

Describe alternatives you've considered
Currently have to downgrade @koa/router to v13.X or add additional custom code to add transaction names.

Additional context

v15.0.0 drops support for node.js 18.