Add SetTellPositionRequest schema and minor cleanup.

Added a new `SetTellPositionRequest` schema in `schemas.py` to support bulk updates of TELL positions. Commented out redundant metadata operations in `main.py` and cleaned up unused content in the test notebook for better readability.

backend/app/models.py

@@ -208,6 +208,7 @@ class PuckEvent(Base):
 
     id = Column(Integer, primary_key=True, index=True)
     puck_id = Column(Integer, ForeignKey("pucks.id"))
+    tell = Column(String(255), nullable=True)
     tell_position = Column(String(255), nullable=True)
     event_type = Column(String(255), index=True)
     timestamp = Column(DateTime, default=datetime.now)