[UI/UX] Implement Global UX Rules

[ucguy4u]

Part of #178 - UI/UX Architecture Improvements

Purpose: Ensure consistent UX across all tabs

Global UX Rules to Implement:

1. Each tab has one primary intent - no feature overlap
2. No cross-tab UI pollution
3. Persistent music player appears ONLY in Beats + Stream tabs
4. Greetings appear ONLY in Mind tab
5. Quotes/inspiration ONLY in Mind tab

Implementation Tasks:

• Create MiniPlayerVisibility provider to control player visibility
• Update AppShell to conditionally show mini player based on current route
• Remove greeting widgets from non-Mind tabs
• Remove quote widgets from non-Mind tabs
• Audit all tabs for cross-tab pollution

Files to Update:

• app/lib/core/app/app_shell.dart
• app/lib/features/music/presentation/widgets/mini_player.dart
• app/lib/features/iptv/presentation/widgets/iptv_mini_player.dart
• Remove DailyQuoteCard from money_overview_screen.dart