feat(cli): add page-size configuration option for changelog pagination

[devin-ai-integration]

Description

Refs #12006

Adds a page-size configuration option for changelog navigation items in docs.yml. This allows users to control how many changelog entries are displayed per page.

Companion PR: https://github.com/fern-api/fern-platform/pull/6837 (adds pageSize to FDR ChangelogNode type)

Changes Made

• Added page-size property to ChangelogConfiguration in the docs.yml schema
• Updated ParsedDocsConfiguration to include pageSize on changelog items
• Updated parseDocsConfiguration.ts to parse the new property
• Updated ChangelogNodeConverter to pass pageSize through to the FDR node
• Updated DocsDefinitionResolver to pass pageSize when creating changelog nodes
• Added CLI version 3.63.0 changelog entry

Example Usage

navigation:
  - changelog: ./changelog
    page-size: 10  # Display 10 entries per page

Testing

• Lint checks pass (pnpm run check)
• Manual testing (requires fern-platform PR to be merged first)

Human Review Checklist

• Verify the fern-platform companion PR is merged before this PR
• Verify page-size → pageSize property mapping is correct in serialization
• Note: pageSize is only supported on changelog navigation items, not on tabbed changelog tabs (this is intentional based on the schema)

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Link to Devin run: https://app.devin.ai/sessions/9f9efc959e4a4fbfba758b6926a201f1
Requested by: Catherine Deskur

[devin-ai-integration]

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