[#74366] Adapt PDF exports for semantic identifiers

[judithroth]

This was rushed a bit because I wanted to get this done before my vacation 😅
This adapts different exports and is probably best reviewed commit by commit.
If you don't see the need for changes and approve, also merge it please!

Ticket

https://community.openproject.org/wp/74366 / https://community.openproject.org/wp/74754

What are you trying to accomplish?

Use semantic IDs in PDF exports for

• work package details
• work package lists

This also improves the output of a work package with other linked work packages in the description for the "Contract" Template. Before, the links would not have been expanded (e.g. "##124" would be part of the PDF instead of the nicer expanded representation). This was solved with a shared module.

Out of scope (will be fully covered with https://community.openproject.org/wp/74755):

• PDF export of meetings

Merge checklist

• Added/updated tests
• Added/updated documentation in Lookbook (patterns, previews, etc)
• Tested major browsers (Chrome, Firefox, Edge, ...)

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adapts PDF export output to use semantic (formatted/display) work package identifiers instead of raw numeric IDs, and extends mention handling so work package mentions render with the correct identifier format.

Changes:

• Replace numeric ID rendering in multiple PDF exports (titles, tables, Gantt labels) with display_id / formatted_id.
• Centralize work package mention expansion into a shared module and reuse it across PDF markdown generators.
• Add/adjust specs to validate classic vs semantic identifier output for filenames, Gantt strings, and markdown mention expansion.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
spec/models/work_packages/pdf_export/work_package_to_pdf_spec.rb	Updates expectations to use formatted_id in headings.
spec/models/work_packages/pdf_export/work_package_list_to_pdf_spec.rb	Updates list/detail expectations to use display_id.
spec/models/work_packages/pdf_export/work_package_list_to_pdf_gantt_spec.rb	Uses formatted_id in Gantt labels; adds classic vs semantic assertions.
spec/models/work_package/pdf_export/document_generator_spec.rb	Adds coverage for filename titles and WP mentions in descriptions.
spec/models/exports/pdf/common/markdown/md2_pdf_export_spec.rb	New spec file covering mention expansion in classic vs semantic mode.
app/models/work_package/pdf_export/work_package_to_pdf.rb	Uses formatted_id / display_id in heading and filename.
app/models/work_package/pdf_export/generator/generator.rb	Adds WP mention rendering using shared mention expander.
app/models/work_package/pdf_export/document_generator.rb	Uses display_id in filename generation.
app/models/exports/pdf/components/gantt/gantt_builder.rb	Uses formatted_id in work package info line.
app/models/exports/pdf/common/work_package_mentions.rb	New shared module to expand WP mentions consistently.
app/models/exports/pdf/common/markdown.rb	Removes duplicated mention expansion/date helpers in favor of shared module.
app/models/exports/pdf/common/common.rb	Changes ID column cell rendering to use display_id link caption.