Enhance changelog bundle command with github release workflow

[lcawl]

Summary

Per #2841, the docs-builder changelog gh-release command creates both changelog files and a bundle from a GitHub release. This PR enhances the docs-builder changelog bundle command to also be able to do just the second half of that functionality, in case teams want to separate the tasks. For example, maybe there's a case where they already have all the changelogs (created on a PR-by-PR basis) and just want to bundle up the appropriate changelogs for a release.

Files changed

• Config model:

  • BundleConfiguration.cs — added Repo and Owner properties (derived from outstanding Changelog profile parity - phase 1 & 2 #2791)
  • ChangelogConfigurationYaml.cs (BundleConfigurationYaml) — added Repo and Owner for YAML deserialization
  • ChangelogConfigurationLoader.cs — maps the new fields in ParseBundleConfiguration

• src/tooling/docs-builder/Commands/ChangelogCommand.cs

  • added --release-version and using Elastic.Documentation.ReleaseNotes; to the Bundle method; when set: validates mutual exclusivity with --all/--input-products/--prs/--issues and requirement of --repo, fetches the release, parses PR references from the release notes, builds full PR URLs, auto-infers --output-products from the tag+repo when not explicitly provided, then passes the PR list to the existing ChangelogBundlingService flow
  • Bundle's --release-version block now:
    • Loads ChangelogConfiguration first (before the repo check)
    • Resolves resolvedRepo as --repo CLI → bundle.repo config
    • Resolves resolvedOwner as --owner CLI → bundle.owner config → "elastic"
    • Only errors if neither CLI nor config provides a repo (with an updated message)
    • Uses resolvedRepo throughout (fetch, PR URL construction, product auto-inference)

• tests/Elastic.Changelog.Tests/Changelogs/BundleReleaseVersionTests.cs (new) — 6 tests covering: PR list bundling from release, auto-inferred output products, explicit output products override, no PR refs warning, fetch failure, and latest tag pass-through

• Docs:

  • changelog-bundle.md — documented --release-version option with all its constraints; updated the four existing filter option descriptions to mention it in the mutual exclusivity note; added a "Bundle by GitHub release" subsection with examples; updated --repo description
  • contribute/changelog.md — added --release-version to the filter options list; added "Bundle by GitHub release" subsection with example and auto-inference note; updated to drop the hard "requires --repo" wording and show both the repo and owner precedence chains

All 250 tests pass.

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

2. If you answered "Yes" to the previous question, please specify the tool(s) and model(s) used (e.g., Google Gemini, OpenAI ChatGPT-4, etc.).

Tool(s) and model(s) used: composer-1.5, clause-4.6-sonnet-medium