Add docs pages for 2025 projects

[khaeru]

This PR adds docs pages for fifteen (15) projects mentioned in the 2025-01 projects overview (internal link) that were not so far mentioned anywhere in the MESSAGEix(-GLOBIOM) documentation.

We could expand this PR to:

• Update CODEOWNERS making the designated LM of the respective project the owner of the documentation page.
• Accept direct commits or PRs into this branch to populate the pages, all currently empty. This could be, initially, a transcription of the slide contents.

How to review

TBD, see above.

• View the preview build of the docs and confirm the project title is spelled and capitalized correctly.

PR checklist

• Continuous integration checks all ✅
• Add or expand tests; coverage checks both ✅
• Add, expand, or update documentation.
• Update doc/whatsnew.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.7%. Comparing base (080d9a5) to head (572cb62).
Report is 6 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #282   +/-   ##
=====================================
  Coverage   76.7%   76.7%           
=====================================
  Files        211     211           
  Lines      16108   16108           
=====================================
  Hits       12363   12363           
  Misses      3745    3745           

see 28 files with indirect coverage changes