fix(app): fix sidebar crash when switching iOS theme

Unistyles' StyleSheet.create((theme) => ...) wraps styled components in
<UnistylesComponent> and patches native view properties via C++. When
these dynamic styles are applied to Reanimated's Animated.View, a theme
change causes both systems to fight over the same native node, crashing
with "Unable to find node on an unmounted component."

Fix: use plain React Native StyleSheet for static positioning on
Animated.View, and pass theme-dependent values (backgroundColor) as
inline styles from useUnistyles() instead of Unistyles dynamic sheets.

Also:
- Add gestureAnimatingRef to prevent double withTiming during gesture opens
- Remove all debug instrumentation added during investigation
- Add Maestro flow and bash script for automated theme-toggle verification
- Add docs/MOBILE_TESTING.md covering Maestro patterns, self-verification
  loops, the Unistyles+Reanimated pitfall, and simulator commands

packages/app/maestro/.gitignore

@@ -0,0 +1,2 @@
+# Maestro takeScreenshot artifacts
+*.png