docs: align retrieval-pipeline with multi-release version filtering

[detail-app]

Corrects three areas of docs/retrieval-pipeline.md that drifted after the retrieval layer switched from a single-version client-side filter pattern to multi-release server-side filtering:

• The "Metadata filter generation" section described the deleted extractFilterPatterns() / VersionFilterPatterns.matchesMetadata() client-side fallback flow and the singular RetrievalConstraint.forDocVersion(versionNumber) API. Replaced with the actual extractVersionNumbers() -> RetrievalConstraint.docVersions (any-of matchKeywords) -> per-release fan-out with requireRequestedVersionEvidence fail-fast enforcement. A reader following the old doc would look for classes/methods that no longer exist and assume a client-side URL/title post-filter fallback that was removed.
• The query boosting example showed release features documentation, but the word "features" was dropped from boostQueryWithVersionContext; updated to match actual output and noted multi-release queries produce ;-separated prefixes.
• The deduplication table listed the content-hash key as hash; it is now docVersion + hash so the same chunk can appear once per requested release.

Introduced by commit 4f70a7e (@WilliamAGH)

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