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.go

@@ -186,7 +186,14 @@ func (p *AdventurePlugin) OnMessage(ctx MessageContext) error {
 		return p.handleDMReply(ctx)
 	}
 
-	// 3. Command dispatch
+	// 3. NPC encounter tracking — count room messages from adventure players
+	if !isDM && !strings.HasPrefix(ctx.Body, "!") {
+		safeGo("npc-track", func() {
+			p.npcTrackMessage(ctx.Sender)
+		})
+	}
+
+	// 4. Command dispatch
 	if !p.IsCommand(ctx.Body, "adventure") && !p.IsCommand(ctx.Body, "adv") {
 		return nil
 	}
@@ -559,6 +566,8 @@ func (p *AdventurePlugin) resolvePendingInteraction(ctx MessageContext, interact
 		return p.resolveShopConfirm(ctx, interaction)
 	case "hospital_pay":
 		return p.resolveHospitalPay(ctx, interaction)
+	case "npc_encounter":
+		return p.resolveNPCEncounter(ctx, interaction)
 	}
 	return nil
 }