Tune tolerance value

I have validated that the tolerance value for both arcs and Bézier segments is calibrated correctly. Thus, it makes sense to set both to a value of 0.25, so that caps are consistent. This comes quite close to matching the amount of subdivision in current main, and the line count is also consistent between CPU and GPU stroke expansion.

src/cpu_shader/flatten.rs

diff --git a/src/cpu_shader/flatten.rs b/src/cpu_shader/flatten.rs
index aa2a77a..a69fc5d 100644
--- a/src/cpu_shader/flatten.rs
+++ b/src/cpu_shader/flatten.rs
@@ -164,7 +164,7 @@
 
     let mut p0 = transform.apply(begin);
     let mut r = begin - center;
-    let tol: f32 = 0.1;
+    let tol: f32 = 0.25;
     let radius = tol.max((p0 - transform.apply(center)).length());
     let theta = (2. * (1. - tol / radius).acos()).max(MIN_THETA);