Add rival duels, babysitting service, multilingual !define, economy tuning

Rival System:
- RPS-based duels between combat level 5+ players (best of 3, ties re-prompt)
- Stakes scale with level, split 50/50 between winner and community pot
- 3-4 day randomized challenge interval, 7-day same-pair cooldown
- 24h response window with auto-forfeit
- Full flavor text pools, character sheet integration, !adventure rivals

Babysitting Service:
- Weekly/monthly auto-play service targeting weakest skill
- Babysitter rerolls death, claims items, credits gold and XP
- Rivals automatically declined during service
- End-of-service summary with diaper report

Revive fixes:
- On-demand revive in handleMenu, parseAndResolveChoice, handleStatus
- Morning DM respawn check now runs before babysit interception
- Players no longer stuck dead after DeadUntil expires mid-day

Other changes:
- Multilingual !define searches all DreamDict languages by default
- TwinBee empty haul now shows "jackshit" instead of blank
- Wordle solve payouts increased (e.g. 1-guess: €100 -> €500)
- Per-message euro payouts doubled across all tiers
- Audit fixes: user locks on RPS/babysit handlers, TOCTOU on gold
  transfers, dead code removal, deprecated strings.Title replaced,
  error logging on silent failures

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

internal/plugin/adventure_arena.go

@@ -369,6 +369,9 @@ func (p *AdventurePlugin) resolveArenaSurvival(ctx MessageContext, run *ArenaRun
 	}
 	char.CombatXP += battleXP
 	leveled, newLevel := checkAdvLevelUp(char, "combat")
+	if leveled {
+		p.checkRivalPoolUnlock(char)
+	}
 	if err := saveAdvCharacter(char); err != nil {
 		slog.Error("arena: failed to save character after survival", "user", ctx.Sender, "err", err)
 	}
@@ -538,7 +541,9 @@ func (p *AdventurePlugin) resolveArenaDeath(ctx MessageContext, run *ArenaRun, c
 	now := time.Now().UTC()
 	char.ArenaLosses++
 	char.CombatXP += arenaParticipationXP // +60 flat participation XP
-	checkAdvLevelUp(char, "combat")
+	if leveled, _ := checkAdvLevelUp(char, "combat"); leveled {
+		p.checkRivalPoolUnlock(char)
+	}
 	if err := saveAdvCharacter(char); err != nil {
 		slog.Error("arena: failed to save character after death", "user", ctx.Sender, "err", err)
 	}