Memory minigame: repeat an emoji or color sequence on a 3x3 board

A new minigame where you memorise a sequence and repeat it by clicking. It uses the same 3x3 button board as Tic-Tac-Toe.

Two variants:
- Emoji order: 9 emojis sit on the board and the bot shows a sequence, e.g. 🍎 ⭐ 🔥. Then the board is shuffled and you click the emojis in the same order.
- Color memory (Simon style): fields light up one after another in four colors (🟥 🟦 🟩 🟨) and you repeat the order. Every round you get right adds one step.

Rules:
- One wrong click or the timeout ends the game.
- Score is the longest sequence reached; the points reward grows with it.
- Optional bet, like in Tic-Tac-Toe.
- Solo against the bot, or 1v1: both players get the same sequence and the longer streak wins.
- Difficulty: easy uses 4 fields, hard uses all 9 fields and faster playback.
- Personal best and a server leaderboard for the longest sequence.

Notes for the team:
- Discord buttons only have three colored styles plus grey, so the four colors come from square emojis on the buttons.
- Playing back the sequence takes one message edit per step, so the speed has to stay within Discord's edit rate limit. Fallback: show the whole sequence as text for a few seconds, then hide it.
- Its own sub-feature toggle under Mini Games, like tictactoe.

Use case

A quick solo or 1v1 game in chat that tests memory instead of luck. Slots, Crash and Rock Paper Scissors all depend on chance.

Benefit

Adds a game based on skill, reuses the existing Tic-Tac-Toe board and gives players a streak record to beat, which keeps them replaying and active on the leaderboard.