Add models and utils with type hints and optimizations

Models (6 + 1 association table):
- User: Authentication with bcrypt, admin role check, last_login tracking
- Player: Digital signage devices with auth codes, status tracking, online detection
- Group: Player/content organization with statistics properties
- Content: Media files with type detection, file size helpers, position ordering
- ServerLog: Audit trail with class methods for logging levels
- PlayerFeedback: Player status updates with error tracking
- group_content: Many-to-many association table for groups and content

Model improvements:
- Added type hints to all methods and properties
- Added database indexes on frequently queried columns (username, auth_code, group_id, player_id, position, level, timestamp, status)
- Added comprehensive docstrings
- Added helper properties (is_online, is_admin, file_size_mb, etc.)
- Added relationship back_populates for bidirectional navigation
- Added timestamps (created_at, updated_at, last_seen, uploaded_at)

Utils (4 modules):
- logger.py: Logging utility with level-based functions (info, warning, error)
- uploads.py: File upload handling with progress tracking, video optimization
- group_player_management.py: Player/group status tracking and bulk operations
- pptx_converter.py: PowerPoint to PDF conversion using LibreOffice

Utils improvements:
- Full type hints on all functions
- Comprehensive error handling
- Progress tracking for long-running operations
- Video optimization (H.264, 30fps, max 1080p, 8Mbps)
- Helper functions for time formatting and statistics
- Proper logging of all operations

Performance optimizations:
- Database indexes on all foreign keys and frequently filtered columns
- Lazy loading for relationships where appropriate
- Efficient queries with proper ordering
- Helper properties to avoid repeated calculations

Ready for template migration and testing

app/models/player_feedback.py

@@ -0,0 +1,64 @@
+"""Player feedback model for tracking player status and errors."""
+from datetime import datetime
+from typing import Optional
+
+from app.extensions import db
+
+
+class PlayerFeedback(db.Model):
+    """Player feedback model for tracking player status updates.
+    
+    Attributes:
+        id: Primary key
+        player_id: Foreign key to player
+        status: Current status (playing, paused, error, unknown)
+        current_content_id: ID of currently playing content
+        message: Optional status message
+        error: Optional error message
+        timestamp: Feedback timestamp
+    """
+    __tablename__ = 'player_feedback'
+    
+    id = db.Column(db.Integer, primary_key=True)
+    player_id = db.Column(db.Integer, db.ForeignKey('player.id'), 
+                         nullable=False, index=True)
+    status = db.Column(db.String(50), nullable=False, default='unknown')
+    current_content_id = db.Column(db.Integer, db.ForeignKey('content.id'), 
+                                   nullable=True)
+    message = db.Column(db.Text, nullable=True)
+    error = db.Column(db.Text, nullable=True)
+    timestamp = db.Column(db.DateTime, default=datetime.utcnow, 
+                         nullable=False, index=True)
+    
+    # Relationships
+    player = db.relationship('Player', back_populates='feedback')
+    content = db.relationship('Content', backref='feedback_entries')
+    
+    def __repr__(self) -> str:
+        """String representation of PlayerFeedback."""
+        return f'<PlayerFeedback Player={self.player_id} Status={self.status}>'
+    
+    @property
+    def is_error(self) -> bool:
+        """Check if feedback indicates an error."""
+        return self.status == 'error' or self.error is not None
+    
+    @property
+    def age_seconds(self) -> float:
+        """Get age of feedback in seconds."""
+        delta = datetime.utcnow() - self.timestamp
+        return delta.total_seconds()
+    
+    @classmethod
+    def get_latest_for_player(cls, player_id: int) -> Optional['PlayerFeedback']:
+        """Get most recent feedback for a player.
+        
+        Args:
+            player_id: Player ID to query
+            
+        Returns:
+            Latest PlayerFeedback instance or None
+        """
+        return cls.query.filter_by(player_id=player_id)\
+            .order_by(cls.timestamp.desc())\
+            .first()