Add restore functionality for archived messages

- Added `RestoreMessageHandler` and route at `/account/messages/restore`
- Updated `users_messages` table to support `archived_at` reset
- Added restore button to archived messages template
- Ensures archived messages can be moved back into inbox

storage/messages.go

@@ -127,3 +127,52 @@ func GetArchivedMessages(db *sql.DB, userID int, page, perPage int) []models.Mes
 	}
 	return messages
 }
+
+func GetInboxMessages(db *sql.DB, userID int, page, perPage int) []models.Message {
+	offset := (page - 1) * perPage
+	rows, err := db.Query(`
+		SELECT id, senderId, recipientId, subject, message, is_read, created_at
+		FROM users_messages
+		WHERE recipientId = ? AND is_archived = FALSE
+		ORDER BY created_at DESC
+		LIMIT ? OFFSET ?
+	`, userID, perPage, offset)
+	if err != nil {
+		return nil
+	}
+	defer rows.Close()
+
+	var messages []models.Message
+	for rows.Next() {
+		var m models.Message
+		err := rows.Scan(
+			&m.ID, &m.SenderId, &m.RecipientId,
+			&m.Subject, &m.Message, &m.IsRead, &m.CreatedAt,
+		)
+		if err == nil {
+			messages = append(messages, m)
+		}
+	}
+	return messages
+}
+
+func GetInboxMessageCount(db *sql.DB, userID int) int {
+	var count int
+	err := db.QueryRow(`
+		SELECT COUNT(*) FROM users_messages
+		WHERE recipientId = ? AND is_archived = FALSE
+	`, userID).Scan(&count)
+	if err != nil {
+		return 0
+	}
+	return count
+}
+
+func RestoreMessage(db *sql.DB, userID, messageID int) error {
+	_, err := db.Exec(`
+		UPDATE users_messages
+		SET is_archived = FALSE, archived_at = NULL
+		WHERE id = ? AND recipientId = ?
+	`, messageID, userID)
+	return err
+}