Add blacksmith repair system, community lottery, and audit fixes

Blacksmith: equipment repair with tier-based pricing, DM confirmation flow,
masterwork/arena surcharges, full flavor text pools. Added to main adventure
menu as option 6 (rest bumped to 7).

Lottery: weekly draw (Friday 23:59 UTC), ticket purchases with 100/week cap,
Fisher-Yates number generation, fixed+jackpot prize tiers, community pot
funding, Thursday reminders, draw history.

Audit fixes: TOCTOU in blacksmith repair costs (recompute from fresh equipment),
user lock in DM slot selection, partial repair refund tracking, error logging
on save failures, Fisher-Yates bias correction, communityPotDebit return value
checks in draw execution.

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

internal/plugin/lottery_draw.go

@@ -0,0 +1,272 @@
+package plugin
+
+import (
+	"fmt"
+	"log/slog"
+	"strings"
+	"time"
+
+	"gogobee/internal/db"
+
+	"maunium.net/go/mautrix/id"
+)
+
+// ── Prize Tiers (fixed payouts) ─────────────────────────────────────────────
+
+var lotteryFixedPrizes = map[int]int{
+	4: 1000,
+	3: 100,
+	2: 10,
+	1: 2,
+}
+
+// ── Draw Ticker ─────────────────────────────────────────────────────────────
+
+func (p *LotteryPlugin) drawTicker() {
+	ticker := time.NewTicker(1 * time.Minute)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		now := time.Now().UTC()
+		if now.Weekday() != time.Friday || now.Hour() != 23 || now.Minute() != 59 {
+			continue
+		}
+
+		weekKey := lotteryCurrentWeekStart()
+		jobName := "lottery_draw"
+		if db.JobCompleted(jobName, weekKey) {
+			continue
+		}
+
+		slog.Info("lottery: executing weekly draw")
+		p.executeDraw(weekKey)
+		db.MarkJobCompleted(jobName, weekKey)
+	}
+}
+
+// ── Reminder Ticker ─────────────────────────────────────────────────────────
+
+func (p *LotteryPlugin) reminderTicker() {
+	ticker := time.NewTicker(1 * time.Minute)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		now := time.Now().UTC()
+		if now.Weekday() != time.Thursday || now.Hour() != 20 || now.Minute() != 0 {
+			continue
+		}
+
+		weekKey := lotteryCurrentWeekStart()
+		jobName := "lottery_reminder"
+		if db.JobCompleted(jobName, weekKey) {
+			continue
+		}
+
+		gr := gamesRoom()
+		if gr != "" {
+			pot := communityPotBalance()
+			p.SendMessage(gr, fmt.Sprintf(
+				"🎟️ Lottery draw tomorrow. 23:59 UTC. Current pot: €%d. "+
+					"Tickets €1 each. Max 100 per player. `!lottery buy [N]` to enter.",
+				pot))
+		}
+
+		db.MarkJobCompleted(jobName, weekKey)
+	}
+}
+
+// ── Draw Execution ──────────────────────────────────────────────────────────
+
+func (p *LotteryPlugin) executeDraw(weekStart string) {
+	winning := generateLotteryNumbers()
+
+	tickets, err := lotteryLoadAllWeekTickets(weekStart)
+	if err != nil {
+		slog.Error("lottery: failed to load tickets for draw", "err", err)
+		return
+	}
+
+	if len(tickets) == 0 {
+		gr := gamesRoom()
+		if gr != "" {
+			p.SendMessage(gr, "🎟️ **LOTTERY DRAW** — No tickets were sold this week. The pot rolls over.")
+		}
+		return
+	}
+
+	// Score all tickets.
+	matchBuckets := make(map[int][]lotteryTicket) // matchCount -> tickets
+	for i := range tickets {
+		mc := countMatches(tickets[i].Numbers, winning)
+		tickets[i].MatchCount = &mc
+
+		prize := 0
+		if mc >= 1 && mc <= 4 {
+			prize = lotteryFixedPrizes[mc]
+		}
+		tickets[i].Prize = &prize
+
+		lotteryUpdateTicketResult(tickets[i].ID, mc, prize)
+		matchBuckets[mc] = append(matchBuckets[mc], tickets[i])
+	}
+
+	pot := communityPotBalance()
+	initialPot := pot
+
+	// Calculate fixed tier payouts.
+	fixedTotal := 0
+	for tier := 4; tier >= 1; tier-- {
+		count := len(matchBuckets[tier])
+		fixedTotal += count * lotteryFixedPrizes[tier]
+	}
+
+	// If pot can't cover all fixed payouts, prorate top-down.
+	actualFixed := fixedTotal
+	if actualFixed > pot {
+		actualFixed = pot
+	}
+
+	// Debit fixed payouts from pot.
+	if actualFixed > 0 {
+		if !communityPotDebit(actualFixed) {
+			slog.Error("lottery: failed to debit fixed payouts from pot", "amount", actualFixed)
+			actualFixed = 0
+		}
+		pot -= actualFixed
+	}
+
+	// Credit fixed tier winners.
+	prorateRatio := 1.0
+	if fixedTotal > 0 && actualFixed < fixedTotal {
+		prorateRatio = float64(actualFixed) / float64(fixedTotal)
+	}
+
+	if actualFixed > 0 {
+		for tier := 4; tier >= 1; tier-- {
+			for _, t := range matchBuckets[tier] {
+				amount := int(float64(lotteryFixedPrizes[tier]) * prorateRatio)
+				if amount > 0 {
+					p.euro.Credit(t.UserID, float64(amount), fmt.Sprintf("lottery_%dmatch", tier))
+				}
+			}
+		}
+	}
+
+	// Jackpot.
+	jackpotWinners := matchBuckets[5]
+	jackpotAmount := 0
+	rolledOver := 0
+
+	if len(jackpotWinners) > 0 && pot >= 500 {
+		// Split remaining pot among jackpot winners.
+		perWinner := pot / len(jackpotWinners)
+		remainder := pot - (perWinner * len(jackpotWinners))
+		jackpotAmount = perWinner
+
+		totalJackpotDebit := perWinner * len(jackpotWinners)
+		if !communityPotDebit(totalJackpotDebit) {
+			slog.Error("lottery: failed to debit jackpot from pot", "amount", totalJackpotDebit)
+			// Jackpot rolls over — don't credit winners.
+			jackpotAmount = 0
+			rolledOver = pot
+		} else {
+			for _, t := range jackpotWinners {
+				p.euro.Credit(t.UserID, float64(perWinner), "lottery_jackpot")
+				lotteryUpdateTicketResult(t.ID, 5, perWinner)
+			}
+			rolledOver = remainder
+		}
+	} else {
+		// Jackpot rolls over.
+		rolledOver = pot
+	}
+
+	// Insert history.
+	h := &lotteryHistoryRow{
+		DrawDate:       time.Now().UTC().Format("2006-01-02"),
+		WinningNumbers: winning,
+		JackpotWinners: len(jackpotWinners),
+		JackpotAmount:  jackpotAmount,
+		Match4Winners:  len(matchBuckets[4]),
+		Match3Winners:  len(matchBuckets[3]),
+		Match2Winners:  len(matchBuckets[2]),
+		Match1Winners:  len(matchBuckets[1]),
+		PotTotal:       initialPot,
+		RolledOver:     rolledOver,
+	}
+	lotteryInsertHistory(h)
+
+	// Room announcement.
+	gr := gamesRoom()
+	if gr != "" {
+		announcement := p.buildDrawAnnouncement(winning, h, jackpotWinners)
+		p.SendMessage(gr, announcement)
+	}
+
+	// Cleanup old tickets.
+	lotteryCleanupOldTickets()
+
+	slog.Info("lottery: draw completed",
+		"winning", winning,
+		"tickets", len(tickets),
+		"pot", initialPot,
+		"jackpot_winners", len(jackpotWinners))
+}
+
+// ── Announcement Builder ────────────────────────────────────────────────────
+
+func (p *LotteryPlugin) buildDrawAnnouncement(winning []int, h *lotteryHistoryRow, jackpotWinners []lotteryTicket) string {
+	var sb strings.Builder
+
+	sb.WriteString("🎟️ **LOTTERY DRAW** — Friday 23:59 UTC\n\n")
+	sb.WriteString(fmt.Sprintf("This week's numbers: **%s**\n\n", formatLotteryNumbers(winning)))
+
+	// Jackpot line.
+	if len(jackpotWinners) > 0 && h.JackpotAmount > 0 {
+		names := p.resolveWinnerNames(jackpotWinners)
+		if len(jackpotWinners) == 1 {
+			sb.WriteString(fmt.Sprintf("Jackpot (5 match): **%s** — €%d 🎉\n", names[0], h.JackpotAmount))
+		} else {
+			sb.WriteString(fmt.Sprintf("Jackpot (5 match): Split between %s. €%d each. 🎉\n",
+				joinNames(names), h.JackpotAmount))
+		}
+	} else if len(jackpotWinners) > 0 && h.JackpotAmount == 0 {
+		sb.WriteString("Jackpot withheld — pot insufficient. Rolls to next week. Fixed tiers paid as normal.\n")
+	} else {
+		sb.WriteString("Jackpot (5 match): No winner this week. Pot rolls over.\n")
+	}
+
+	// Fixed tiers.
+	sb.WriteString(fmt.Sprintf("4 match: %d winner(s) — €1,000 each\n", h.Match4Winners))
+	sb.WriteString(fmt.Sprintf("3 match: %d winner(s) — €100 each\n", h.Match3Winners))
+	sb.WriteString(fmt.Sprintf("2 match: %d winner(s) — €10 each\n", h.Match2Winners))
+	sb.WriteString(fmt.Sprintf("1 match: %d winner(s) — €2 each\n", h.Match1Winners))
+
+	distributed := h.PotTotal - h.RolledOver
+	sb.WriteString(fmt.Sprintf("\nPot distributed: €%d. Next draw: Friday. Tickets on sale now.", distributed))
+
+	return sb.String()
+}
+
+func (p *LotteryPlugin) resolveWinnerNames(winners []lotteryTicket) []string {
+	// Deduplicate by user ID (multiple tickets from same player).
+	seen := make(map[id.UserID]bool)
+	var names []string
+	for _, t := range winners {
+		if seen[t.UserID] {
+			continue
+		}
+		seen[t.UserID] = true
+		// Try to get display name from DM room.
+		name := p.DisplayName(t.UserID)
+		names = append(names, name)
+	}
+	return names
+}
+
+func joinNames(names []string) string {
+	if len(names) <= 2 {
+		return strings.Join(names, " and ")
+	}
+	return strings.Join(names[:len(names)-1], ", ") + ", and " + names[len(names)-1]
+}