[Chessing234]

Running gen_degree.py outside the repository root writes Degree{n}.lean into the caller's working directory. Resolve the output directory from the script path and create Sendov/FiniteRange when needed, so the generated proof lands in the source tree.

Validation: the numerical --check suite passes. Generation from a different working directory passes with both an absent and an existing output directory; the file is written under Sendov/FiniteRange and no file appears in the caller's directory. git diff --check passes. No Lean source changes are included.

Replaces #5 with a clean commit history. The separate import-guard proposal in #2 addresses a different behavior.