fix: reduce scroll catch-up steps to limit jitter (#219)

Reduce max_steps from 0.1s to 0.04s of catch-up time (from 5 to 2 steps
at 50 FPS). When the system lags, the previous catch-up logic allowed
jumping up to 5 pixels at once, causing visible jitter. Limiting to 2
steps provides smoother scrolling while still allowing for minor timing
corrections.

Co-authored-by: Chuck <chuck@example.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/common/scroll_helper.py

@@ -240,7 +240,7 @@ class ScrollHelper:
                 # Move pixels (can move multiple steps if lag occurred, but cap to prevent huge jumps)
                 steps = int(time_since_last_step / self.scroll_delay)
                 # Cap at reasonable number to prevent huge jumps from lag
-                max_steps = max(1, int(0.1 / self.scroll_delay))  # Allow up to 0.1s of catch-up
+                max_steps = max(1, int(0.04 / self.scroll_delay))  # Limit to 0.04s (2 steps at 50 FPS) for smoother scrolling
                 steps = min(steps, max_steps)
                 pixels_to_move = self.scroll_speed * steps
                 # Update last_step_time, preserving fractional delay for smooth timing