release: publish trendfollowing 1.1.0

[ArturSepp]

Summary

• prepare the approved non-breaking trendfollowing 1.1.0 adoption release
• synchronize project, citation, README, changelog, runtime, and documentation versions
• clear the declared Ruff E/F/W gate across package code, tests, and root examples, with narrow F401 exceptions only for intentional re-export modules
• fix the maintainer-only undefined credit_df entry and make screener output honor TF_FIGURE_PATH

Verification

• pytest tests/ -q: 56 passed, 1 skipped
• ruff check src/trendfollowing tests examples: passed
• ARFIMA variance-scale verification: passed, published values unchanged
• EWMA variance verification: passed, published values unchanged
• Sphinx HTML and linkcheck with -W --keep-going: passed
• python -m build and twine check dist/*: passed
• wheel and sdist installed separately outside the checkout; quickstart, packaged load_data(), and pip check passed in both
• wheel SHA-256: f5a2d9f6ab514f9c0771108c142c0b7586ec54557c4d865c1412a218b5176049
• sdist SHA-256: c33c7fe755b1b185698ab91fa4da7299f55afeead2f65c5f91449ae0adcc515e

Publication remains gated on this PR's CI and merge. PyPI upload, tag creation, and GitHub Release creation will use the merged commit only.