Sanitize codebase, reorganize docs, and add missing deploy files

Remove dead code identified in docs/SANITIZATION-REVIEW.md:
- app/blueprints/content_old.py and app/blueprints/playlist.py
- app/models/group.py, app/utils/nginx_config_reader.py
- orphaned templates (content_list, edit_content, upload_content,
  player_page) and the related group/Template references

Result: 6 blueprints, 82 routes, no dead modules or orphan templates.

Add files that deploy.sh and docker-entrypoint.sh already require but
which were never tracked:
- https_manager.py       (referenced by deploy.sh, migrate_network.sh,
                          docker-entrypoint.sh)
- Caddyfile.example      (seeded by deploy.sh; its absence aborts deploy)

Relocate generated Graphify artifacts from graphify-out/ to
docs/graphify-out/ (110 files, no content change) and archive the
superseded docs under docs/.

Ignore hygiene:
- ignore ad-hoc .env backups (.env.bak*) — they contain live secrets
- keep the pre-sanitization snapshots (docs/legacy code/,
  docs/old_code_documentation/) on disk but out of the repo

Fix .env.example: drop a duplicated config block, genericize the
hardcoded host IP, and document HOSTNAME_INTERNAL.

app/models/__init__.py

@@ -1,7 +1,6 @@
 """Models package for digiserver-v2."""
 from app.models.user import User
 from app.models.player import Player
-from app.models.group import Group, group_content
 from app.models.playlist import Playlist, playlist_content
 from app.models.content import Content
 from app.models.server_log import ServerLog
@@ -13,7 +12,6 @@ from app.models.https_config import HTTPSConfig
 __all__ = [
     'User',
     'Player',
-    'Group',
     'Playlist',
     'Content',
     'ServerLog',
@@ -21,6 +19,5 @@ __all__ = [
     'PlayerEdit',
     'PlayerUser',
     'HTTPSConfig',
-    'group_content',
     'playlist_content',
 ]

app/models/content.py

@@ -38,8 +38,6 @@ class Content(db.Model):
     # Relationships - many-to-many with playlists
     playlists = db.relationship('Playlist', secondary='playlist_content', 
                                back_populates='contents', lazy='dynamic')
-    groups = db.relationship('Group', secondary='group_content', 
-                            back_populates='contents', lazy='dynamic')
     
     def __repr__(self) -> str:
         """String representation of Content."""
@@ -52,11 +50,6 @@ class Content(db.Model):
             return round(self.file_size / (1024 * 1024), 2)
         return 0.0
     
-    @property
-    def group_count(self) -> int:
-        """Get number of groups containing this content."""
-        return self.groups.count()
-
     @property
     def original_display_name(self) -> str:
         """Name of the original (unedited) file for display purposes."""

app/models/group.py

@@ -1,66 +0,0 @@
-"""Group model for organizing players and content."""
-from datetime import datetime
-from typing import List, Optional
-
-from app.extensions import db
-
-
-# Association table for many-to-many relationship between groups and content
-group_content = db.Table('group_content',
-    db.Column('group_id', db.Integer, db.ForeignKey('group.id'), primary_key=True),
-    db.Column('content_id', db.Integer, db.ForeignKey('content.id'), primary_key=True)
-)
-
-
-class Group(db.Model):
-    """Group model for organizing players with shared content.
-    
-    Attributes:
-        id: Primary key
-        name: Unique group name
-        description: Optional group description
-        created_at: Group creation timestamp
-        updated_at: Last modification timestamp
-    """
-    __tablename__ = 'group'
-    
-    id = db.Column(db.Integer, primary_key=True)
-    name = db.Column(db.String(100), nullable=False, unique=True, index=True)
-    description = db.Column(db.Text, nullable=True)
-    created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)
-    updated_at = db.Column(db.DateTime, default=datetime.utcnow, 
-                          onupdate=datetime.utcnow, nullable=False)
-    
-    # Relationships
-    contents = db.relationship('Content', secondary=group_content, 
-                              back_populates='groups', lazy='dynamic')
-    
-    def __repr__(self) -> str:
-        """String representation of Group."""
-        return f'<Group {self.name} (ID={self.id})>'
-    
-
-    
-    @property
-    def content_count(self) -> int:
-        """Get number of content items in this group."""
-        return self.contents.count()
-    
-    def add_player(self, player) -> None:
-        """Add a player to this group.
-        
-        Args:
-            player: Player instance to add
-        """
-        player.group_id = self.id
-        self.updated_at = datetime.utcnow()
-    
-    def remove_player(self, player) -> None:
-        """Remove a player from this group.
-        
-        Args:
-            player: Player instance to remove
-        """
-        if player.group_id == self.id:
-            player.group_id = None
-            self.updated_at = datetime.utcnow()

app/models/player.py

@@ -19,7 +19,7 @@ class Player(db.Model):
         orientation: Display orientation (Landscape/Portrait)
         status: Current player status (online, offline, error)
         last_seen: Last activity timestamp
-        playlist_version: Version number for playlist synchronization
+        playlist_id: Assigned playlist (sync version comes from Playlist.version)
         created_at: Player creation timestamp
     """
     __tablename__ = 'player'