Improve handling of network drops in daily puzzles

[bglw]

Sequence of operations:

• Playing daily puzzle, sending moves to server
• Each move receives the current "daily stats" from the server
• Connection dies (network change, etc)
• Sending moves to server silently fails
• Win the game, which opens up the splash screen with the most recent "daily stats" (from a few turns ago)
• Does not show the win
• Click replay, new attempt is tracked as of whenever connection comes back

High level fixes:

• Stop requesting / storing the daily stats ahead of time
• At the end of the game require that all moves are synced to the server (wait for successful response)
  • Show some kind of loading screen / spinner until this comes back
• Only request daily stats when pulling up splash screen
  • Likewise, show some loading spinner while waiting for the latest stats
  • Make the loading text fit better
• Add nonces to all outgoing messages
  • Send acknowledgements from the server
  • Store messages in a new queue for "unacknowledged"
  • Remove from this queue on ack
  • On a new ws connection setup, re-send all unacknowledged messages