Closes #606

Route Astropy WCS projections through a native AstroAxes bridge instead of the external container, preserve per-axes transform dispatch for SubplotGrid, and keep shared panel labels stable for both cartesian and astro axes.

Move logical ticklabel state access into the axes classes so Figure can share and hand off panel labels without branching on cartesian, geo, and astro subplot types.

Make the Astropy WCS bridge a true optional import by loading and registering AstroAxes only on WCS-specific access, while keeping the panel/share refactors and import behavior covered by tests.

Make Astropy a true opt-in runtime extra by adding dedicated package extras for Astro, geographic, and ternary integrations, along with an all extra that installs the optional runtime stack without changing the default UltraPlot dependency set.

At the same time, tighten the Astro axes import path so explicit WCS usage fails with a clear installation message instead of silently returning None. astro.py is now treated as an Astropy-backed module again, the lazy loader in axes.__init__ raises a targeted ImportError with the recommended install command, and WCS string resolution in projections.py now relies on that explicit failure path.

This also expands inline documentation in AstroAxes to make the WCS override points clearer, and updates the import tests to match the new optional-dependency behavior.

Add a dedicated Astropy WCS section to docs/usage.rst so the new AstroAxes integration is discoverable from the main usage guide. The section explains the optional install path, shows the two supported creation patterns (direct WCS objects and the "wcs" alias), and clarifies that UltraPlot handles figure-level sharing/layout while advanced coordinate customization still lives on ax.coords[...].

Revert the non-sharing left and bottom panel relabeling that shifted shared subplot labels and broke existing image baselines. Also harden the Astro lazy-import test so missing astropy does not crash the subprocess before the optional import path is exercised.

…projection-606

# Conflicts:
#	ultraplot/axes/__init__.py