Add --skip-compare-text option

[JustusRijke]

Summary

• Adds --skip-compare-text CLI flag and skip_compare_text API parameter to bypass the text content comparison stage
• Useful when different PDF render engines produce identical-looking PDFs with different text extraction order, which would otherwise cause false positive failures

Test plan

• test_skip_compare_text — verifies skipping text stage still catches visual differences
• test_skip_compare_text_multiplatform — verifies multiplatform PDFs pass with flag enabled
• test_skip_compare_text_flag — verifies CLI flag wires through correctly

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!