docs: add Option, Result, Exception, Callback, Wire-Format and Cross-Monad-Bridges pages Replace the placeholder Home with a navigation hub and ship one page per building block. Each page covers the why, the API surface and common before/after patterns where the library replaces a concrete anti-pattern. Wire-Format documents the round-trip contract for Option/Result/Exception including subclass identity preservation and the deliberate stack-dropping policy. Cross-Monad-Bridges covers the two conversion functions and when not to reach for them.