When Clublog returns HTTP 403 (access denied), automatically clear the stored credentials and optionally send the user an email notification with context about the failure. Also sets a session flash warning when the affected user is logged in. Adds an email view template for the notification.
Introduces a new `station_profile.clublogcron` flag (migration 276) and wires it into station create/edit save flows so users can explicitly enable locations for `/clublog/upload`. Clublog station selection now only includes enabled locations (with fallback to `clublogrealtime` if the new column is not present), and the dashboard shows a warning when Clublog credentials exist but no station is enabled. It also tightens Clublog upload-status query grouping and fixes `Clublog::uploadall` return flow so upload results are returned consistently.
