Handle spoiler edits in messages

[BK1031]

Adds a Discord message update handler to detect and delete spoilers in edited messages.

This prevents users from circumventing the spoiler filter by editing an already sent message to include spoiler content.

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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[netlify]

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[Copilot]

Pull Request Overview

This PR adds functionality to detect and delete spoiler content in edited Discord messages, preventing users from circumventing the spoiler filter by editing already-sent messages to include forbidden content.

• Adds a new Discord message update event handler (OnMessageUpdate)
• Implements spoiler detection logic using regex patterns and string matching for edited messages
• Provides automatic deletion of messages containing spoilers with user notification

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[BK1031]

lgtm!