Fix NumPy array handling for plot limits

[dhruvb2028]

What does this PR do?

prepare_for_plot() currently checks for empty limits using limits == [].
For NumPy arrays, this performs an element-wise comparison and can raise a
broadcasting error.

This PR replaces that comparison with a length check, updates the pairplot()
and marginal_plot() type hints to include NumPy arrays, and adds a regression
test verifying that NumPy limits are applied to the correct plot axes.

Does this close any issues?

Addresses the NumPy limits item in #1978.

Anything else we should know?

Validation performed:

• uv run pytest tests/plot_test.py: 496 passed, 9 xfailed.
• Ruff check and formatting checks passed for the changed files.
• uv run pyright sbi: 0 errors.
• Pre-commit hooks passed for the changed files.
• The non-slow, non-GPU suite completed with 6601 passed, 38 skipped, 120
  xfailed, and three environment-related PyTensor failures. Those three tests
  passed when rerun using PyTensor's Python fallback instead of the incompatible
  local MinGW compiler.

Checklist

• I have read the contributing guide.
• uv run pytest -n auto -m "not slow and not gpu" passes.
• uv run pre-commit run --all-files passes (ruff and formatting).
• uv run pyright sbi passes.
• I added or updated tests for the changed behavior.
• I used Google-style docstrings for new or changed public functions.
• (If applicable) I reported how long new tests run and marked slow ones
  with pytest.mark.slow.

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 900821d and c246ef8.

📒 Files selected for processing (2)

• sbi/analysis/plot.py
• tests/plot_test.py

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

Changes

NumPy plot limits

Layer / File(s)	Summary
Accept and validate NumPy limits sbi/analysis/plot.py, tests/plot_test.py	marginal_plot and pairplot accept NumPy array limits. prepare_for_plot checks empty limits by length. A regression test verifies diagonal and off-diagonal axis bounds.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to c246e

This localized change fixes NumPy plot-limit handling and adds regression coverage; no actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: janfb

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: fixing NumPy array handling for plot limits.
Description check	✅ Passed	The description explains the problem, solution, affected functions, issue reference, regression test, validation results, and checklist status. It also documents the three environment-related test fai…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description explains the problem, solution, affected functions, issue reference, regression test, validation results, and checklist status. It also documents the three environment-related test failures and their fallback reruns.

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[dhruvb2028]

I noticed after opening this PR that @BHARATH0153 had already described a fix for item 1 in #1978. I’m sorry I missed that comment. I couldn’t find a linked PR or public branch for the change, so could you confirm whether that work is still active?