Added Performance Links and Per-Instance Sync Overrides

Tessitura-powered sites can now use performance-link redirects and choose which attributes sync automatically per instance. Connection-state messaging is also clearer when a test fails or a web mode of sale is not active.

Per-instance sync overrides

Sync attribute configuration previously applied globally across all events. Individual instances can now override which attributes sync automatically, leaving the global sync map and the rest of the season untouched.

Clearer connection states

When a connection test fails or a web mode of sale is not active, the admin shows a specific error message rather than a generic failure state. This makes configuration safer to review before a season goes live.