Add zarr-globe example

> Written by Claude on behalf of @kylebarron

## Context

The globe-view prototype (#563, part of #82) added a COG globe example (`examples/cog-globe`). The Zarr-path globe example was scoped out of that PR.

## Task

Add `examples/zarr-globe`: copy `examples/dynamical-zarr-ecmwf` and set `projection="globe"` on the `` (it already renders deck.gl interleaved). The global ECMWF 0.25° dataset is a good whole-globe demo. The shared globe render path from #563 already handles `ZarrLayer`, so this should be a thin example wrapper plus the projection change.

## Links

- Follow-up to #563; part of #82.