feat(sdks): add parsers[].pages for per-page PDF markdown (#4353)

* feat(sdks): add parsers[].pages for per-page PDF markdown

Expose the renamed v2 PDF parser pages option (formerly pageMarkdown)
and Document.pages across the JS, Python, Go, Java, Ruby, PHP, Rust,
and .NET SDKs. Bump each package version so merge auto-publishes.

Co-authored-by: Abimael Martell <abimaelmartell@users.noreply.github.com>

* fix(python-sdk): fold deprecated pageMarkdown into pages

Pydantic dropped page_markdown/pageMarkdown on PDFParser before
prepare_scrape_options could rewrite them. Accept both aliases on
the model so they serialize as pages.

Co-authored-by: Abimael Martell <abimaelmartell@users.noreply.github.com>

* fix(python-sdk): drop unreachable pageMarkdown folds on model dump

PDFParser already folds page_markdown/pageMarkdown into pages in a
before-validator, so model_dump cannot emit those keys. Keep the
alias rewrite only on the raw-dict parser branch.

Co-authored-by: Abimael Martell <abimaelmartell@users.noreply.github.com>

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Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Abimael Martell <abimaelmartell@users.noreply.github.com>