Cascading meta to a sub-tree of routes

[vwong]

Currently meta files +meta.json needs to exist per +page.marko. We can't cascade the same meta file for an entire sub-tree of routes at once. Such a capability could be quite useful to set default meta, and only overriding/augmenting where it makes sense. Perhaps something like https://www.11ty.dev/docs/data-cascade/

Can we have such a feature?