Add iterable collection combinators to true-myth

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What this task asks for

Add iterable-aware sequence, traverse, zip, filtering, and task combinators across Maybe, Result, Task, and toolbelt APIs. Make `Maybe` and `Result` implement `[Symbol.iterator]` and `Task` implement `[Symbol.asyncIterator]`. The async iterator must yield exactly one `Result`: `Ok` for a resolved task and `Err` for a rejected one. Add `sequence`, `traverse`, `zip`, and `zipWith` to `maybe`, `result`, and `task`. Add `compact` and `filterMap` to `maybe` (drop failures silently). Add `traverseSerial` to `task` (sequential, stops on first rejection) with non-curried signature `traverseSerial(items, fn)` and a curried form `traverseSerial(fn)` returning `(items) => result`. Add `retryN(n, fn)` to `task` to retry a task-producing function up to `n` additional times on rejection.