Added three new tests to verify the deskew acceptance criteria:
- test_deskew_2_degree_skew: Verifies 2-degree skew is deskewed within 0.1 deg
- test_deskew_0_2_degree_skew_skipped: Verifies 0.2-degree skew is skipped
- test_deskew_20_degree_skew_out_of_range: Verifies out-of-range diagnostic
Helper function create_skewed_text_lines() creates synthetic test images
with known skew angles using small-angle trigonometric approximations.
Note: Tests compile but cannot run without leptonica library (NixOS limitation).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
