feat: new slash commands and bug fixes (#23)

## Summary

- **feat**: Add `/remind` owner-only command — sends a meeting waiting room notification to a specified user in `#general`
- **fix**: Prevent duplicate DM notifications when a message matches both `respondToMention` and `notifyNameMention` patterns
- **feat**: Port `/alt-text` and `/query` commands from Cordelia — owner-only, AI-powered, using Amari's personality
- **feat**: Add `/research` command — owner-only, web-search-backed query returning results as a markdown file attachment
- **fix**: Suppress non-critical RetroAchievements fetch errors (job retries every 10 minutes)

Closes #19, #20, #21, #22
Also resolves #2 (unhandled HTTP rejections from RA API)

Reviewed-on: #23
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src/events/handleMessageCreate.ts

@@ -29,6 +29,8 @@ export const handleMessageCreate = async(
     amari.recentlyActiveChannels.add(message.channel.id);
   }
   await updateMentorshipThread(amari, message);
-  await respondToMention(amari, message);
-  await notifyNameMention(amari, message);
+  const mentionNotified = await respondToMention(amari, message);
+  if (!mentionNotified) {
+    await notifyNameMention(amari, message);
+  }
 };