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/sidebar-theme-repro.yaml

@@ -0,0 +1,31 @@
+appId: sh.paseo
+---
+# Ensure sidebar is closed: if sidebar-sessions is visible, close it via swipe left
+- runFlow:
+    when:
+      visible:
+        id: "sidebar-sessions"
+    commands:
+      - swipe:
+          direction: LEFT
+          duration: 300
+
+# Small pause for close animation
+- takeScreenshot: 00-sidebar-closed
+
+# Open sidebar via swipe right gesture (the actual path that triggers the bug)
+- swipe:
+    start: "5%,50%"
+    end: "80%,50%"
+    duration: 300
+
+# Verify sidebar opened
+- assertVisible:
+    id: "sidebar-sessions"
+- takeScreenshot: 01-sidebar-opened
+
+# Close sidebar via swipe left
+- swipe:
+    direction: LEFT
+    duration: 300
+- takeScreenshot: 02-sidebar-closed-again