Enhance CMEMS → dfsu example: include uo/vo, infer n_points, and add horizontal flip option

[tile-timley]

In the CMEMS → dfsu example (https://dhi.github.io/mikeio/examples/dfsu/cmems_vertical_profile.html), it would be useful to:

• include the vector components uo and vo in the example workflow
• infer n_points automatically from the CMEMS grid rather than requiring it as a manual input
• add an option/function to flip the horizontal orientation of the extracted output (potentially only needed for dfs2; dfsu with lat/lon may already handle this automatically?)

[ecomodeller]

Addressed in #952:

• n_points: added inline hint showing how to infer from grid resolution
• uo/vo: added as commented example in the variables dict — the workflow is identical to temperature/salinity