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_db.go

@@ -0,0 +1,190 @@
+package plugin
+
+import (
+	"encoding/json"
+	"log/slog"
+	"time"
+
+	"gogobee/internal/db"
+
+	"maunium.net/go/mautrix/id"
+)
+
+// ── Types ───────────────────────────────────────────────────────────────────
+
+type lotteryTicket struct {
+	ID         int64
+	UserID     id.UserID
+	WeekStart  string
+	Numbers    []int
+	MatchCount *int
+	Prize      *int
+}
+
+type lotteryHistoryRow struct {
+	DrawDate       string
+	WinningNumbers []int
+	JackpotWinners int
+	JackpotAmount  int
+	Match4Winners  int
+	Match3Winners  int
+	Match2Winners  int
+	Match1Winners  int
+	PotTotal       int
+	RolledOver     int
+}
+
+// ── Week Helpers ────────────────────────────────────────────────────────────
+
+// lotteryCurrentWeekStart returns Monday of the current week as "2006-01-02".
+func lotteryCurrentWeekStart() string {
+	now := time.Now().UTC()
+	weekday := int(now.Weekday())
+	if weekday == 0 {
+		weekday = 7 // Sunday = 7
+	}
+	monday := now.AddDate(0, 0, -(weekday - 1))
+	return monday.Format("2006-01-02")
+}
+
+// ── Ticket CRUD ─────────────────────────────────────────────────────────────
+
+func lotteryTicketCount(userID id.UserID, weekStart string) int {
+	d := db.Get()
+	var count int
+	_ = d.QueryRow(`SELECT COUNT(*) FROM lottery_tickets WHERE user_id = ? AND week_start = ?`,
+		string(userID), weekStart).Scan(&count)
+	return count
+}
+
+func lotteryTotalTicketCount(weekStart string) int {
+	d := db.Get()
+	var count int
+	_ = d.QueryRow(`SELECT COUNT(*) FROM lottery_tickets WHERE week_start = ?`, weekStart).Scan(&count)
+	return count
+}
+
+func lotteryInsertTickets(userID id.UserID, weekStart string, tickets [][]int) {
+	d := db.Get()
+	for _, nums := range tickets {
+		data, _ := json.Marshal(nums)
+		_, err := d.Exec(`INSERT INTO lottery_tickets (user_id, week_start, numbers) VALUES (?, ?, ?)`,
+			string(userID), weekStart, string(data))
+		if err != nil {
+			slog.Error("lottery: failed to insert ticket", "user", userID, "err", err)
+		}
+	}
+	// Each ticket costs €1 — add to community pot.
+	communityPotAdd(len(tickets))
+}
+
+func lotteryLoadUserTickets(userID id.UserID, weekStart string) ([]lotteryTicket, error) {
+	d := db.Get()
+	rows, err := d.Query(`SELECT id, user_id, week_start, numbers, match_count, prize
+		FROM lottery_tickets WHERE user_id = ? AND week_start = ? ORDER BY id`,
+		string(userID), weekStart)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	return scanLotteryTickets(rows)
+}
+
+func lotteryLoadAllWeekTickets(weekStart string) ([]lotteryTicket, error) {
+	d := db.Get()
+	rows, err := d.Query(`SELECT id, user_id, week_start, numbers, match_count, prize
+		FROM lottery_tickets WHERE week_start = ? ORDER BY id`, weekStart)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	return scanLotteryTickets(rows)
+}
+
+func lotteryUpdateTicketResult(ticketID int64, matchCount, prize int) {
+	d := db.Get()
+	_, err := d.Exec(`UPDATE lottery_tickets SET match_count = ?, prize = ? WHERE id = ?`,
+		matchCount, prize, ticketID)
+	if err != nil {
+		slog.Error("lottery: failed to update ticket result", "id", ticketID, "err", err)
+	}
+}
+
+// ── History CRUD ────────────────────────────────────────────────────────────
+
+func lotteryInsertHistory(h *lotteryHistoryRow) {
+	d := db.Get()
+	winJSON, _ := json.Marshal(h.WinningNumbers)
+	_, err := d.Exec(`INSERT INTO lottery_history
+		(draw_date, winning_numbers, jackpot_winners, jackpot_amount,
+		 match4_winners, match3_winners, match2_winners, match1_winners,
+		 pot_total, rolled_over)
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+		h.DrawDate, string(winJSON), h.JackpotWinners, h.JackpotAmount,
+		h.Match4Winners, h.Match3Winners, h.Match2Winners, h.Match1Winners,
+		h.PotTotal, h.RolledOver)
+	if err != nil {
+		slog.Error("lottery: failed to insert history", "err", err)
+	}
+}
+
+func lotteryLoadHistory(limit int) ([]lotteryHistoryRow, error) {
+	d := db.Get()
+	rows, err := d.Query(`SELECT draw_date, winning_numbers, jackpot_winners, jackpot_amount,
+		match4_winners, match3_winners, match2_winners, match1_winners,
+		pot_total, rolled_over
+		FROM lottery_history ORDER BY draw_date DESC LIMIT ?`, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var history []lotteryHistoryRow
+	for rows.Next() {
+		var h lotteryHistoryRow
+		var winJSON string
+		if err := rows.Scan(&h.DrawDate, &winJSON, &h.JackpotWinners, &h.JackpotAmount,
+			&h.Match4Winners, &h.Match3Winners, &h.Match2Winners, &h.Match1Winners,
+			&h.PotTotal, &h.RolledOver); err != nil {
+			return nil, err
+		}
+		_ = json.Unmarshal([]byte(winJSON), &h.WinningNumbers)
+		history = append(history, h)
+	}
+	return history, rows.Err()
+}
+
+// ── Cleanup ─────────────────────────────────────────────────────────────────
+
+func lotteryCleanupOldTickets() {
+	d := db.Get()
+	_, err := d.Exec(`DELETE FROM lottery_tickets WHERE week_start < DATE('now', '-30 days')`)
+	if err != nil {
+		slog.Error("lottery: failed to cleanup old tickets", "err", err)
+	}
+}
+
+// ── Scan Helper ─────────────────────────────────────────────────────────────
+
+type lotteryRows interface {
+	Next() bool
+	Scan(dest ...interface{}) error
+	Err() error
+}
+
+func scanLotteryTickets(rows lotteryRows) ([]lotteryTicket, error) {
+	var tickets []lotteryTicket
+	for rows.Next() {
+		var t lotteryTicket
+		var numsJSON string
+		var matchCount, prize *int
+		if err := rows.Scan(&t.ID, &t.UserID, &t.WeekStart, &numsJSON, &matchCount, &prize); err != nil {
+			return nil, err
+		}
+		_ = json.Unmarshal([]byte(numsJSON), &t.Numbers)
+		t.MatchCount = matchCount
+		t.Prize = prize
+		tickets = append(tickets, t)
+	}
+	return tickets, rows.Err()
+}