Refactor brand assets and runtime app icon changes

[mixin27]

Description

• Refreshed brand assets and launcher icons:
  • New night-sky visual direction with glowing full-moon style.
  • Updated Play Store feature graphic output.
  • Regenerated Android, iOS/macOS, and web icon assets from branding generator.
• Expanded selectable app icon variants in settings:
  • Default
  • Moon
  • Forest
  • Minimal Flat
  • Premium Dark
  • Traditional Myanmar
• Improved dynamic app-icon switching behavior:
  • Added stronger iOS switching guards and retry handling for transient LaunchServices failures (NSPOSIXErrorDomain code=35).
  • Improved method-channel flow for icon selection and state synchronization.
  • Added alternate icon metadata compatibility fallback in iOS Info.plist.
• Added native setup recovery tooling for maintainability:
  • scripts/restore_native_mobile_setup.sh to restore Android icons/widgets and iOS icon setup from git.
  • scripts/verify_native_mobile_setup.sh to verify native integration contracts.
  • Added architecture documentation: docs/architecture/native_mobile_setup.md.
• Fixed first-launch calendar language inconsistency:
  • Unified fallback defaults so calendar runtime, settings page, reset flow, and home-widget background updates all use Myanmar (my) by default.
• Important platform note:
  • iOS Simulator may not reliably support alternate icon switching (known LaunchServices limitation).
  • Validate icon switching on a physical iOS device or cloud real-device environment.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore