Add Attendance OCR to track event participation and stats from in-game screenshots

[justncodes]

Add Attendance OCR

Logging who took part in an event (and how much they contributed) currently means reading screenshots by eye and entering everything into attendance, which is tedious. This adds a channel where members simply upload screenshots from the relevant event, and the bot reads the names and numbers off the image, matches them to the alliance roster, and lets you record the attendance results and scores with minimal effort.

As a bonus from being able to read in screenshots, we can now track player power - both Power and Combat Power - from the respective screenshots. Supporting improvements to the attendance, registration, and member-management flows are added too, including Discord ID tracking.

What it reads

You upload the in-game event mail screenshots - the sign-up list and/or the post-battle results - for:

• Foundry Battle and Canyon Clash: both the sign-ups (who registered + their Power) and the results (points and ranking, plus per-player battle stats: fuel used, enemy squads defeated, buildings occupied, speed-ups, march accelerators, retreats, advances, and MVPs).
• Power Rankings and Alliance Showdown: results screens - WIP.

How it works

1. Pick a channel and choose which events it should accept.
2. A member (or admin-only) drops one screenshot or more from the same event into that channel.
3. The bot works out which event it is, reads each player and their stats, and matches the names to the alliance roster.
4. Every match is tagged confirmed / likely / needs review, so you trust the clear ones, check the rest and correct as needed in a quick review screen.
5. Sign-up and results screenshots can arrive at different times, but the bot links them to the same event, and saves the per-player stats alongside attendance (members' Power is refreshed too).

No more manual entry.

Still to do, possibly before merge

• Improve the support for Alliance Showdown
• Add support for more events (wherever possible)
• Improve the interface to provide detailed data on player power, history etc. now that we can track power
• Testing and more testing of OCR with screenshots. Especially with non-Latin alphabets to make sure we support all in-game interface languages properly
• Merge Attendance and Bear Track into one unified score + attendance + power tracking etc. feature... (likely a future PR)