chore: carve paper figures/eval out of the package; fix CI collection

[nathanchenseanwalter]

Move all manuscript figure-generation code, paper/benchmark eval scripts, their detection/PR-sweep helpers, and the paper tests into the gitignored dev/paper/ tree so they no longer ship in the wheel or break CI.

• src/tokeye/extra/eval/{events,sweep,fold_stats}.py -> dev/paper/eval/ (extra/eval now ships only the silbidopy + D3D loaders)
• scripts/eval/*.py + .ipynb -> dev/paper/eval/; eval_.sh + ablation/eval.sh -> dev/paper/eval/commands/ (paths updated); scripts/test_ablation_smoke.py too
• output/nature_figures -> dev/paper/figures (was already untracked)
• 7 paper/ablation tests -> dev/paper/tests/ with a conftest that puts dev/paper/eval on sys.path; tests/ keeps only core + dep-free ablation tests
• moved scripts/tests now import the helpers locally (from sweep/events/ fold_stats) instead of tokeye.extra.eval.*

CI: the four collection errors (h5py/pybaselines/tifffile/lightning) are gone because the tests importing tokeye.training.big_tf_unet_ablation.step_* moved out of tests/. Also:

• add [project.optional-dependencies] train so pip install tokeye[train] works
• align CI python matrix to 3.13/3.14 (matches requires-python >=3.13)