refacto: enhancements

Refacto and few improvements for simplification:

• simplify overall code structure (scripts, tests, package) and some patterns (e.g. the Ensembler ABC, using typed class variables when possible)
• fix some tests (+ add mandelli as flaky) (~ 85% coverage)
• keep sidbench detectors' but "deactivate" it (installation in Makefile and xfail in tests) as weights are no longer available at repo url and it is not possible to reproduce (should probably create a dedicated issue to follow-up on that)
• switch to mkdocs
• switch to uv
• bump reuse version
• slightly clearer logging
• update CI : run CI only manually for MR and on main. running the tests of detectors is still TBC (➕ relevant coverage, reproducibility, ... ➖ very long to run in CI, heavy on our resources and a bit flaky depending on runner / may timeout)
• add streamlit app from @vamblard (👏 thx for the first contrib to this amazing project)
• update doc

Closes #110 (closed) #109 (closed)