Add forex plugin, stability fixes, and async HTTP dispatch

- Add forex plugin (Frankfurter v2 API) with rate lookups, analysis,
  DM-based alerts, and daily cron poll. Backfills 1 year of history
  on startup for moving averages and buy signal scoring.

- Fix bot hang caused by SQLite lock contention in reminder polling:
  rows cursor was held open while writing to the same DB. Collect
  results first, close cursor, then process. Same fix in milkcarton.

- Add sync retry loop so the bot reconnects after network drops
  instead of silently exiting. StopSync() for clean Ctrl+C shutdown.

- Add panic recovery to all dispatch, syncer, and cron paths.

- Make all HTTP-calling plugin commands async (goroutines) so a slow
  or dead external API cannot block the message dispatch pipeline.
  Affects: lookup, stocks, forex, anime, movies, concerts, gaming,
  retro, wotd, urls, howami.

- Extract DisplayName to Base, add db.Exec helper, convert silent
  error discards across the codebase.

- Fix UNO mercy-kill bug (eliminated bot continues playing), adventure
  DM nag spam, stats column mismatch, per-call regex/replacer allocs.

- Update README: forex commands, Finance section, 47 plugins.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/plugin/lookup.go

@@ -48,16 +48,24 @@ func (p *LookupPlugin) Init() error { return nil }
 func (p *LookupPlugin) OnReaction(_ ReactionContext) error { return nil }
 
 func (p *LookupPlugin) OnMessage(ctx MessageContext) error {
+	var handler func(MessageContext) error
 	switch {
 	case p.IsCommand(ctx.Body, "wiki"):
-		return p.handleWiki(ctx)
+		handler = p.handleWiki
 	case p.IsCommand(ctx.Body, "define"):
-		return p.handleDefine(ctx)
+		handler = p.handleDefine
 	case p.IsCommand(ctx.Body, "urban"):
-		return p.handleUrban(ctx)
+		handler = p.handleUrban
 	case p.IsCommand(ctx.Body, "translate"):
-		return p.handleTranslate(ctx)
+		handler = p.handleTranslate
+	default:
+		return nil
 	}
+	go func() {
+		if err := handler(ctx); err != nil {
+			slog.Error("lookup: handler error", "err", err)
+		}
+	}()
 	return nil
 }
 
@@ -266,14 +274,11 @@ func (p *LookupPlugin) handleUrban(ctx MessageContext) error {
 	msg := sb.String()
 
 	// Cache the result
-	_, err = d.Exec(
+	db.Exec("lookup: urban cache",
 		`INSERT INTO urban_cache (term, data, cached_at) VALUES (?, ?, ?)
 		 ON CONFLICT(term) DO UPDATE SET data = ?, cached_at = ?`,
 		termLower, msg, now, msg, now,
 	)
-	if err != nil {
-		slog.Error("lookup: urban cache", "err", err)
-	}
 
 	return p.SendReply(ctx.RoomID, ctx.EventID, msg)
 }