fix(deskew): only require s1 confidence in ObliqueFinder per review

Relax the auto-oblique confidence check to require good confidence only
on the main skew (s1). The rotated sausage mask (s2) may have noisier
confidence; we still use s2.angle() for the oblique difference.

Author: pablogventura

src/core/filters/deskew/ObliqueFinder.cpp

@@ -58,7 +58,8 @@ std::optional<double> findObliqueDegrees(const BinaryImage& mask,
   const Skew s1 = skewFinder.findSkew(mask);
   const Skew s2 = skewFinder.findSkew(rotated);
 
-  if (s1.confidence() < Skew::GOOD_CONFIDENCE || s2.confidence() < Skew::GOOD_CONFIDENCE) {
+  // Only require confidence on the main skew (s1); s2 on the rotated sausage mask may be noisier (review #110).
+  if (s1.confidence() < Skew::GOOD_CONFIDENCE) {
     return std::nullopt;
   }