chore: migrate dependency management to uv

[callebtc]

Summary

• Migrate packaging and dependency management from Poetry to uv with PEP 621 metadata.
• Update CI, Docker, Makefile, docs, and helper scripts to use uv.
• Replace poetry.lock with uv.lock and regenerate requirements.txt from uv.

Verification

• uv sync --locked --python 3.10.4
• uv run python scripts/check_version.py v0.20.2
• uv run cashu --help; uv run mint --help; uv run mint-cli --help
• make ruff-check
• uv build --quiet
• pytest tests/fuzz/test_fuzz_mint_api.py tests/test_core.py tests/test_crypto.py -q
• pytest tests/mint/test_mint_app_router.py tests/mint/test_mint_limit.py tests/mint/test_mint_management_rpc_server.py -q

Full make test was also attempted locally; the broader suite did not complete cleanly because SQLite fixture disk I/O errors appeared after many passing tests.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.74%. Comparing base (19e86e6) to head (60df565).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1075      +/-   ##
==========================================
+ Coverage   75.41%   75.74%   +0.32%     
==========================================
  Files         111      111              
  Lines       12546    12453      -93     
==========================================
- Hits         9462     9432      -30     
+ Misses       3084     3021      -63     

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[a1denvalu3]

1. Remove "setuptools" and "wheel" from standard runtime dependencies in pyproject.toml as they are only required during the build step and are already specified in [build-system].
2. Run uv export --format requirements.txt --no-dev --no-hashes --no-emit-project --output-file requirements.txt