feat(algolia): add facets based on version for search

[haarchri]

When browsing older documentation versions (for example, v1.20), search results currently all content from latest....
This leads to confusion when users discover features or APIs in search results that don’t actually exist in the version they’re viewing.

This PR introduces version-aware search filtering using Algolia facet filters. https://www.algolia.com/doc/guides/managing-results/refine-results/faceting
Search results will be restricted to the documentation version the user is currently viewing.

• Added logic to detect the current page version via .Page.Params.version.
• Configured DocSearch to apply a facetFilters value dynamically:

['docsearch:version:X.XX']

• Added special handling for the master version - uses docsearch:version:0.0.0-master, which matches the existing meta tag convention where master is labeled 0.0.0-master to keep it de-ranked in search

Background

Each page already includes:

which the Algolia crawler indexes.

curl https://docs.crossplane.io/v2.0/composition/  | grep -A 10 "docsearch"
<meta name=docsearch:modified content='August 14, 2025'><meta name=docsearch:version content="2.0">

curl https://docs.crossplane.io/v1.20/concepts/  | grep -A 10 "docsearch"
<meta name=docsearch:modified content='May 21, 2025'><meta name=docsearch:version content="1.20">

Required: Algolia configuration

After this PR is merged, someone with Algolia admin access must enable faceting:

• Open Algolia Dashboard

• Go to the crossplane index

• Navigate to Configuration → Facets

• Add:
  filterOnly(docsearch:version)
  to Attributes for faceting

• Save

Important: The docsearch:version attribute is already indexed, so no re-crawl is required.

Testing:

curl http://localhost:1313/v2.1/composition/ | grep -A 10 "docsearch"
...
<script>
    docsearch({
    container: '#docSearch',
    appId: 'xxx',
    indexName: 'crossplane',
    apiKey: 'xxxxx',
    placeholder: 'Search the docs',
    searchParameters: {
      facetFilters: ['docsearch:version:2.1']
    }
    });
</script>

To verify this PR:

• Open any versioned docs page (for example, /v1.20/concepts/providers/)
• Open DevTools → Network
• Perform a search
• Inspect the request to algolia.net

{"requests":[{"query":"t","indexName":"crossplane","attributesToRetrieve":["hierarchy.lvl0","hierarchy.lvl1","hierarchy.lvl2","hierarchy.lvl3","hierarchy.lvl4","hierarchy.lvl5","hierarchy.lvl6","content","type","url"],"attributesToSnippet":["hierarchy.lvl1:10","hierarchy.lvl2:10","hierarchy.lvl3:10","hierarchy.lvl4:10","hierarchy.lvl5:10","hierarchy.lvl6:10","content:10"],"snippetEllipsisText":"…","highlightPreTag":"<mark>","highlightPostTag":"</mark>","hitsPerPage":20,"clickAnalytics":false,"facetFilters":["docsearch:version:2.0"]}]}

we see the facetFilters

Fixes: #1008

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[haarchri]

This is required because partialCached would cache the first version rendered and reuse it across pages, causing the wrong version filter to be applied.