Docs: preserve wiki section links and PDF documentation versions after How-To migration #1220

Two navigation follow-ups remain after the wiki How-To migration in #1218 (related to #1156).

Preserve incoming wiki section links

The deferred patch in openam-documentation/wiki-migration/wiki-how-to.patch replaces migrated articles with page-level links. It removes the original section headings, so existing links such as wiki/Passwordless-Authenticaion-Methods#conclusion lose their section destination.

Before applying the deferred wiki patch:

• Keep the original headings or equivalent GitHub-compatible anchors in the stubs, including duplicate-heading suffixes where applicable.
• Link each retained section to its corresponding prefixed anchor on the published How-To page, for example passwordless-authentication-methods#passwordless-authentication-methods-conclusion.
• Verify the mapping for all 54 migrated articles and confirm the revised patch applies to the then-current wiki revision.
• Preserve the deployment order: publish and verify the documentation and companion site navigation before updating the wiki. Retained anchors provide section-specific navigation, not automatic HTTP redirects.

Preserve documentation versions in cross-guide PDF links

How-To HTML links can use version-aware Antora xrefs. However, doc-maven-plugin 3.2.2 converts cross-guide xrefs in PDFs to unversioned URLs such as https://doc.openidentityplatform.org/openam/reference/chap-auth-modules.html#data-store-module-ref.

When a release becomes an older documentation version, its PDF therefore continues to point at the current reference. The conversion lives in commons/doc-maven-plugin, in AsciidocToPdfMojo.convertXrefForPdf.

• Define how release/documentation versions are passed to the PDF converter and mapped to site version paths.
• Preserve fragments and current-version behavior while generating version-specific URLs for historical releases.
• Cover cross-guide and cross-component links, including the component landing page, with converter tests and an integration check against the site's actual version paths.

The PDF converter change belongs in the commons repository and can be tracked by a linked implementation issue there when work starts.

Review context: #1218 (review)