fix: player connectivity and media download pipeline

- nginx: add /api/ shortcut block (no portal auth, X-Script-Name /digiserver,
  Host $http_host) so players can reach DigiServer API without /digiserver prefix
- nginx: use $http_host in /api/ block so Flask host_url includes port — fixes
  media download URLs missing :8080 (was http://ip/digiserver/... not http://ip:8080/...)
- player main.py: fix double-port bug when server_ip already contains a port
  (e.g. 192.168.0.230:8080 was producing http://192.168.0.230:8080:80)
- get_playlists_v2.py: force re-sync when server version differs OR local media
  files are missing on disk — fixes stale playlist after server reset
- digiserver api.py: playlist endpoint builds full media URLs using script_root
  from X-Script-Name header set by nginx
- weblink support, player build/deploy improvements, manage-playlist AJAX prefix fix

digiserver-v2/app/models/content.py

@@ -24,6 +24,9 @@ class Content(db.Model):
     content_type = db.Column(db.String(50), nullable=False, index=True)
     duration = db.Column(db.Integer, default=10, nullable=True)
     file_size = db.Column(db.BigInteger, nullable=True)
+    # For 'weblink' content this holds the web page URL to display on the player.
+    # NULL for file-based content (image/video/pdf).
+    url = db.Column(db.String(2048), nullable=True)
     description = db.Column(db.Text, nullable=True)
     uploaded_at = db.Column(db.DateTime, default=datetime.utcnow, 
                            nullable=False, index=True)
@@ -61,3 +64,7 @@ class Content(db.Model):
     def is_pdf(self) -> bool:
         """Check if content is a PDF."""
         return self.content_type == 'pdf'
+    
+    def is_weblink(self) -> bool:
+        """Check if content is a web link (URL) rather than an uploaded file."""
+        return self.content_type == 'weblink'