Improve docs search ranking for API queries

[cvanelteren]

Summary:

• Treat generic query words like function, method, API, and reference as search intent instead of object-name filters.
• Boost API object references and API pages for API-shaped docs searches so queries like format function surface format() reference anchors first.
• Add a JS-backed pytest for the search hook behavior.

Checks:

• black ultraplot/tests/test_docs_search.py
• node --check docs/_static/custom.js
• pytest ultraplot/tests/test_docs_search.py -q
• pytest -n 4 ultraplot/tests/test_docs_search.py ultraplot/tests/test_docs_fetch_releases.py -q
• Simulated the built Sphinx index for format function and confirmed API object anchors are the top displayed results.

[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
ultraplot/tests/test_docs_search.py	87.50%	1 Missing and 1 partial ⚠️

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