Agent Skills: effect-ts

This skill should be used when the user works with Effect (Effect-TS) — writing or reviewing Effect.Service definitions, Layer composition (Layer.provide/provideMerge/mergeAll), Effect.scoped resource handling, converting imperative try/catch/async code to the Effect error channel, deriving types from Schema (Schema-as-SSOT), or testing Effect code with @effect/vitest, TestClock, and Layer-based mocks. Provides generalized design principles and minimal reference patterns for Effect 3.x.