Function navigate 

pub fn navigate(route: &str) -> bool

Navigate to a route (docs/navigation.md).

• "" — pop the innermost stack to its root (falls through outward).
• A single key — RELATIVE: innermost surface first, falling through outward.
• a/b/c — ABSOLUTE: anchor at the outermost surface that knows a, reset every surface inside the anchor to its root, then feed b, c, … inward (surfaces that mount during the cascade consume the rest as they register).
• A trailing ?name=value&… carries route_params to the destination builders.

False = no mounted surface recognized the (first) segment.