[UI/UX] STREAM Tab - IPTV/Live TV Improvements

[ucguy4u]

Part of #187 - UI/UX Architecture Improvements

Tab Purpose

Live TV and streaming content

Required Changes

• AppBar: Title 'Stream' with Search and Cast action icons
• Category filters: All, News, Sports, Entertainment, Music
• Channel list with live indicators
• Video player section (prominent)
• Mini player available within this tab

UX Rules

• IPTV mini player shows here
• No greetings
• No quotes

Files to Modify

• app/lib/features/iptv/presentation/screens/iptv_screen.dart
• app/lib/features/iptv/presentation/widgets/iptv_mini_player.dart