Adopt uv for dependency management and require Python 3.10

[PsiACE]

This is a discussion draft. I propose adopting uv as the primary dependency managerbecause it is currently the best option in the Python ecosystem and lets us lock and unify toolchain dependency versions reliably.

Changes in this draft:

• Replace legacy requirements-*.txt with uv.lock and pyproject.toml extras.
• Update CI workflows and docs to use uv for installs/locks.
• Drop Python 3.9 and standardize on Python 3.10+ across tooling.
• Update Dockerfile to remove 3.9 and use 3.10.

Checklist (tick everything that applies)

• Code linting (required, can be done after the PR checks)
• Documentation
• Tests
• ICLA (required for bigger changes)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.34%. Comparing base (88b2a32) to head (edcd8f9).

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #2085      +/-   ##
==========================================
- Coverage   83.39%   83.34%   -0.04%     
==========================================
  Files         353      353              
  Lines       81696    81769      +73     
  Branches     8634     8993     +359     
==========================================
+ Hits        68123    68148      +25     
- Misses      10750    10796      +46     
- Partials     2823     2825       +2     

see 49 files with indirect coverage changes

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