add claude skills

src/option/CLAUDE.md

@@ -0,0 +1,11 @@
+# Option conventions
+
+- `match()` takes **2 callbacks**: `(onSome, onNone)`
+- `filter()` takes ONLY a predicate — **no errorFactory** (unlike Result)
+- `mapErr()` and `flatMapErr()` do **NOT exist** on Option
+- `none()` returns a frozen singleton
+- `Option.from()` treats only `null | undefined` as None — `0`, `false`, `""` become `Some`
+- `flatMap` callback must return `Option<any>`
+- Async return type: `OptionPromise<T>` — never `Promise<Option<T>>`
+
+See `/native-monad-option` skill for full API reference.