Rebuild radas_dir on change of radas version or radas config only

[tbody-cfs]

Refactors the CI workflow (workflow_actions.yml).

Radas cache

• Key the radas_dir cache on the radas version + radas_config.yaml hash rather than the full poetry.lock, so unrelated dependency bumps no longer bust the cache and force a regeneration.
• Added a force_radas_rebuild workflow_dispatch input that deletes the cache entry and regenerates from scratch — for when a dependency bump does change radas output and the regression tests fail.

Parallel jobs

• Split the monolithic build job into independent test, lint, and docs jobs. lint (pre-commit) and docs (sphinx/doctest/linkcheck) don't need the radas data, so they run in parallel with the tests and surface failures earlier. Release/publish now depend on all three.
• Moved the pandoc install to the docs job, where it's actually used.

Note: need to add Lint (pre-commit) and Documentation to the required status checks on main

[tbody-cfs]

Need to add Lint (pre-commit) and Documentation to the required status checks on main

[MishaVeldhoen]

LGTM - I noticed one issue (that this PR made slightly worse), the linkcheck can fail for reasons unrelated to the PR/build. So requiring it to pass means that a release can be blocked simply because an external server is offline.

Filed a follow-up: #143 to move the linkcheck out of the release CI.