Add Misty & Arina NPCs, fix tier gating, babysit actions, Robbie filter, streak/scheduler bugs

Misty & Arina: random encounter NPCs triggered by chat message counting
(5-10 msg threshold, 7-day cooldown, 7.5% roll). Misty asks for €100 —
accept gives 7-day arena buff (20% gourmet food heals gear + 5 enemy dmg),
decline gives 7-day debuff (20% crowd revenge damage). Arina asks for €5000 —
accept gives 7-day sniper buff (8% instant kill in arena). Effects integrate
into arena round resolution after combat roll; sniper overrides death.

Other fixes:
- Tier gating now uses base skill only — buffs improve success, not access
- Babysitter uses all harvest actions (3/day, 4 on holidays) instead of 1
- Robbie collects all non-equipped items, not just slotted gear
- Robbie timing: fire on first tick >= target hour, not exact minute match
- Streak: dead players who acted still get streak credit
- Streak: dead players skip shame DM (use LastDeathDate, not Alive flag)
- Midnight ticker: in-memory date cache prevents 1439 wasted DB checks/day
- T1 loot values ~3x across all activities to close T1/T2 gap

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

internal/plugin/adventure_arena_combat.go

@@ -13,6 +13,7 @@ type ArenaCombatLog struct {
 	PlayerHP  int
 	EnemyHP   int
 	PlayerWon bool
+	NPCText   string // Misty/Arina effect text, appended to round log
 }
 
 type ArenaCombatRound struct {
@@ -377,6 +378,11 @@ func renderArenaCombatLog(log *ArenaCombatLog, monster *ArenaMonster, won bool,
 		sb.WriteString(fmt.Sprintf("+%d XP (participation) | Back tomorrow.\n", arenaParticipationXP))
 	}
 
+	if log.NPCText != "" {
+		sb.WriteString(log.NPCText)
+		sb.WriteString("\n")
+	}
+
 	return sb.String()
 }