Remove unused xrspatial.analytics module

[brendancol]

Closes #3601

What

• Delete xrspatial/analytics.py (its only function, summarize_terrain, is a thin wrapper over slope/aspect/curvature).
• Delete its test file xrspatial/tests/test_analytics.py.

Why

The function was never exported from xrspatial/__init__.py, never appeared in the README feature matrix or the docs/ API reference, and has no internal callers (repo-wide grep). Callers who want the same result can call slope, aspect, and curvature directly and assemble the Dataset — that's all the wrapper did.

Removing the module breaks the undocumented from xrspatial.analytics import summarize_terrain import path. See #3601 for the discussion of a deprecation-first alternative.

Backend coverage

Not applicable — this only removes code.

Test plan

• python -c "import xrspatial" still works
• pytest xrspatial/tests/ --co collects clean (7616 tests, no import errors)
• No remaining references to summarize_terrain or the analytics module (the one analytics hit left is an unrelated word in a geotiff/_writers/eager.py docstring)

[brendancol]

PR Review: Remove unused xrspatial.analytics module

This PR deletes xrspatial/analytics.py and its test file, nothing else. The usual domain checks (algorithm accuracy, backend dispatch, dask/cupy kernels, performance) don't apply to a straight removal, so I looked at whether anything still depends on the module and whether the removal leaves the tree consistent.

Blockers

None.

Suggestions

The deprecation-first path raised in #3601 is still open. If a maintainer would rather ship a DeprecationWarning for one release than remove outright, that's their call. The PR takes the hard-removal route, which holds up given the function was never public.

Nits

None.

What looks good

• The diff is exactly two file deletions, no stray edits. (I caught and fixed a base-branch issue first: the branch had been cut from a feature branch and was dragging unrelated template work into the diff. A rebase onto origin/main cleaned it up.)
• No remaining importers. A repo-wide grep for summarize_terrain and from xrspatial.analytics comes back empty. The one surviving analytics hit is an unrelated word in a geotiff docstring.
• import xrspatial still works, and pytest --co collects 7616 tests with no import errors from the removed test file.
• Nothing in __init__.py, the README matrix, or docs/ pointed at the module, so there are no dangling doc entries.

Checklist

• Removal leaves no dangling imports or references: verified
• Package still imports: verified
• Test suite collects clean: verified
• No public API or docs entry pointed at the module: verified
• Breaking change (undocumented import path) noted in the PR body and issue: yes