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.go

@@ -0,0 +1,297 @@
+package plugin
+
+import (
+	"fmt"
+	"math/rand/v2"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"maunium.net/go/mautrix"
+)
+
+// ── Plugin ──────────────────────────────────────────────────────────────────
+
+type LotteryPlugin struct {
+	Base
+	euro *EuroPlugin
+}
+
+func NewLotteryPlugin(client *mautrix.Client, euro *EuroPlugin) *LotteryPlugin {
+	return &LotteryPlugin{
+		Base: NewBase(client),
+		euro: euro,
+	}
+}
+
+func (p *LotteryPlugin) Name() string { return "lottery" }
+
+func (p *LotteryPlugin) Commands() []CommandDef {
+	return []CommandDef{
+		{Name: "lottery", Description: "Community lottery — buy tickets, win big", Usage: "!lottery buy [N]", Category: "Games"},
+	}
+}
+
+func (p *LotteryPlugin) Init() error {
+	go p.drawTicker()
+	go p.reminderTicker()
+	return nil
+}
+
+func (p *LotteryPlugin) OnReaction(_ ReactionContext) error { return nil }
+
+func (p *LotteryPlugin) OnMessage(ctx MessageContext) error {
+	if !p.IsCommand(ctx.Body, "lottery") {
+		return nil
+	}
+
+	args := strings.TrimSpace(p.GetArgs(ctx.Body, "lottery"))
+	lower := strings.ToLower(args)
+
+	switch {
+	case lower == "" || lower == "help":
+		return p.handleLotteryHelp(ctx)
+	case lower == "buy" || strings.HasPrefix(lower, "buy "):
+		return p.handleLotteryBuy(ctx, strings.TrimSpace(strings.TrimPrefix(lower, "buy")))
+	case lower == "tickets":
+		return p.handleLotteryTickets(ctx)
+	case lower == "pot":
+		return p.handleLotteryPot(ctx)
+	case lower == "odds":
+		return p.handleLotteryOdds(ctx)
+	case lower == "history":
+		return p.handleLotteryHistory(ctx)
+	}
+
+	return p.SendReply(ctx.RoomID, ctx.EventID, "Unknown lottery command. Try `!lottery help`.")
+}
+
+// ── Commands ────────────────────────────────────────────────────────────────
+
+func (p *LotteryPlugin) handleLotteryHelp(ctx MessageContext) error {
+	text := `🎟️ **Community Lottery**
+
+` + "`!lottery buy [N]`" + ` — Purchase N tickets (default 1, max 100/week). €1 each.
+` + "`!lottery tickets`" + ` — View your tickets for this week's draw
+` + "`!lottery pot`" + ` — Current pot balance and draw countdown
+` + "`!lottery odds`" + ` — Prize tier table and odds
+` + "`!lottery history`" + ` — Last 5 draw results
+
+Draw: Every Friday at 23:59 UTC`
+	return p.SendReply(ctx.RoomID, ctx.EventID, text)
+}
+
+func (p *LotteryPlugin) handleLotteryBuy(ctx MessageContext, args string) error {
+	n := 1
+	if args != "" {
+		parsed, err := strconv.Atoi(args)
+		if err != nil || parsed < 1 {
+			return p.SendReply(ctx.RoomID, ctx.EventID, "Usage: `!lottery buy [N]` where N is 1-100.")
+		}
+		n = parsed
+	}
+
+	weekStart := lotteryCurrentWeekStart()
+	existing := lotteryTicketCount(ctx.Sender, weekStart)
+	remaining := 100 - existing
+
+	if remaining <= 0 {
+		return p.SendReply(ctx.RoomID, ctx.EventID, "You've reached the 100 ticket limit for this week's draw. Come back Friday.")
+	}
+
+	adjusted := false
+	if n > remaining {
+		n = remaining
+		adjusted = true
+	}
+
+	cost := float64(n)
+	if !p.euro.Debit(ctx.Sender, cost, "lottery_tickets") {
+		balance := p.euro.GetBalance(ctx.Sender)
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Tickets cost €1 each. You need €%d but have €%.0f.", n, balance))
+	}
+
+	// Generate tickets.
+	tickets := make([][]int, n)
+	for i := range tickets {
+		tickets[i] = generateLotteryNumbers()
+	}
+
+	lotteryInsertTickets(ctx.Sender, weekStart, tickets)
+
+	// Build confirmation.
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("🎟️ **%d ticket(s) purchased** — €%d\n\n", n, n))
+
+	displayLimit := n
+	if displayLimit > 10 {
+		displayLimit = 10
+	}
+	for i := 0; i < displayLimit; i++ {
+		sb.WriteString(fmt.Sprintf("  #%d  —  %s\n", existing+i+1, formatLotteryNumbers(tickets[i])))
+	}
+	if n > 10 {
+		sb.WriteString(fmt.Sprintf("  ... and %d more\n", n-10))
+	}
+
+	if adjusted {
+		sb.WriteString(fmt.Sprintf("\nAdjusted to %d (weekly cap reached).", n))
+	}
+
+	sb.WriteString(fmt.Sprintf("\nTotal tickets this week: %d/100", existing+n))
+	sb.WriteString(fmt.Sprintf("\nDraw: Friday 23:59 UTC (%s)", lotteryDrawCountdown()))
+
+	return p.SendReply(ctx.RoomID, ctx.EventID, sb.String())
+}
+
+func (p *LotteryPlugin) handleLotteryTickets(ctx MessageContext) error {
+	weekStart := lotteryCurrentWeekStart()
+	tickets, err := lotteryLoadUserTickets(ctx.Sender, weekStart)
+	if err != nil || len(tickets) == 0 {
+		return p.SendReply(ctx.RoomID, ctx.EventID, "🎟️ You have no tickets for this week's draw. `!lottery buy` to get started.")
+	}
+
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("🎟️ **Your tickets this week** (%d):\n\n", len(tickets)))
+
+	displayLimit := len(tickets)
+	if displayLimit > 20 {
+		displayLimit = 20
+	}
+	for i := 0; i < displayLimit; i++ {
+		sb.WriteString(fmt.Sprintf("  #%d  —  %s\n", i+1, formatLotteryNumbers(tickets[i].Numbers)))
+	}
+	if len(tickets) > 20 {
+		sb.WriteString(fmt.Sprintf("  ... and %d more\n", len(tickets)-20))
+	}
+
+	pot := communityPotBalance()
+	sb.WriteString(fmt.Sprintf("\nDraw: Friday 23:59 UTC (%s)  |  Pot: €%d", lotteryDrawCountdown(), pot))
+
+	return p.SendReply(ctx.RoomID, ctx.EventID, sb.String())
+}
+
+func (p *LotteryPlugin) handleLotteryPot(ctx MessageContext) error {
+	weekStart := lotteryCurrentWeekStart()
+	pot := communityPotBalance()
+	totalTickets := lotteryTotalTicketCount(weekStart)
+	countdown := lotteryDrawCountdown()
+
+	text := fmt.Sprintf("🎟️ **Lottery Pot**\n\n"+
+		"Current pot: **€%d**\n"+
+		"Tickets sold this week: %d\n"+
+		"Next draw: Friday 23:59 UTC (%s)\n\n"+
+		"Pot is funded by rival duel shares and ticket sales.",
+		pot, totalTickets, countdown)
+
+	return p.SendReply(ctx.RoomID, ctx.EventID, text)
+}
+
+func (p *LotteryPlugin) handleLotteryOdds(ctx MessageContext) error {
+	text := `🎟️ **Lottery Prize Tiers**
+
+| Match | Prize | Odds (approx.) |
+|-------|-------|----------------|
+| 5 of 5 | Jackpot (split among winners) | 1 in 142,506 |
+| 4 of 5 | €1,000 (fixed) | 1 in 3,062 |
+| 3 of 5 | €100 (fixed) | 1 in 141 |
+| 2 of 5 | €10 (fixed) | 1 in 16 |
+| 1 of 5 | €2 (fixed) | 1 in 4 |
+| 0 of 5 | Nothing | — |
+
+Tickets: €1 each. Max 100 per week. 5 numbers from 1–30.
+Minimum €500 pot required for jackpot payout.`
+
+	return p.SendReply(ctx.RoomID, ctx.EventID, text)
+}
+
+func (p *LotteryPlugin) handleLotteryHistory(ctx MessageContext) error {
+	history, err := lotteryLoadHistory(5)
+	if err != nil || len(history) == 0 {
+		return p.SendReply(ctx.RoomID, ctx.EventID, "🎟️ No draw history yet.")
+	}
+
+	var sb strings.Builder
+	sb.WriteString("🎟️ **Recent Draws**\n\n")
+
+	for _, h := range history {
+		sb.WriteString(fmt.Sprintf("**%s** — %s\n", h.DrawDate, formatLotteryNumbers(h.WinningNumbers)))
+		sb.WriteString(fmt.Sprintf("  Pot: €%d", h.PotTotal))
+		if h.JackpotWinners > 0 {
+			sb.WriteString(fmt.Sprintf("  |  Jackpot: %d winner(s), €%d each", h.JackpotWinners, h.JackpotAmount))
+		}
+		if h.RolledOver > 0 {
+			sb.WriteString(fmt.Sprintf("  |  Rolled over: €%d", h.RolledOver))
+		}
+		sb.WriteString(fmt.Sprintf("\n  4-match: %d  |  3-match: %d  |  2-match: %d  |  1-match: %d\n\n",
+			h.Match4Winners, h.Match3Winners, h.Match2Winners, h.Match1Winners))
+	}
+
+	return p.SendReply(ctx.RoomID, ctx.EventID, sb.String())
+}
+
+// ── Number Generation ───────────────────────────────────────────────────────
+
+func generateLotteryNumbers() []int {
+	// Partial Fisher-Yates on [1..30], take first 5, sort.
+	pool := make([]int, 30)
+	for i := range pool {
+		pool[i] = i + 1
+	}
+	for i := 0; i < 5; i++ {
+		j := i + rand.IntN(30-i)
+		pool[i], pool[j] = pool[j], pool[i]
+	}
+	nums := make([]int, 5)
+	copy(nums, pool[:5])
+	sort.Ints(nums)
+	return nums
+}
+
+func countMatches(ticket, winning []int) int {
+	winSet := make(map[int]bool, len(winning))
+	for _, n := range winning {
+		winSet[n] = true
+	}
+	count := 0
+	for _, n := range ticket {
+		if winSet[n] {
+			count++
+		}
+	}
+	return count
+}
+
+// ── Formatting Helpers ──────────────────────────────────────────────────────
+
+func formatLotteryNumbers(nums []int) string {
+	parts := make([]string, len(nums))
+	for i, n := range nums {
+		parts[i] = strconv.Itoa(n)
+	}
+	return strings.Join(parts, " \u00b7 ")
+}
+
+func lotteryDrawCountdown() string {
+	now := time.Now().UTC()
+	// Find next Friday 23:59.
+	daysUntilFriday := (int(time.Friday) - int(now.Weekday()) + 7) % 7
+	if daysUntilFriday == 0 && (now.Hour() > 23 || (now.Hour() == 23 && now.Minute() >= 59)) {
+		daysUntilFriday = 7
+	}
+	nextDraw := time.Date(now.Year(), now.Month(), now.Day()+daysUntilFriday, 23, 59, 0, 0, time.UTC)
+	d := nextDraw.Sub(now)
+
+	days := int(d.Hours()) / 24
+	hours := int(d.Hours()) % 24
+	mins := int(d.Minutes()) % 60
+
+	if days > 0 {
+		return fmt.Sprintf("%dd %dh %dm", days, hours, mins)
+	}
+	if hours > 0 {
+		return fmt.Sprintf("%dh %dm", hours, mins)
+	}
+	return fmt.Sprintf("%dm", mins)
+}