fix: UDP-logged QSOs fall back to the offline outbox on DB failure (were silently lost); speed up MySQL connect (batch migration checks into 1 query, connect direct-to-DB first) — was ~40s on a high-latency link

internal/db/db.go

@@ -198,14 +198,26 @@ func migrate(conn *sql.DB, translate func(string) string) error {
 	}
 	sort.Strings(names)
 
-	for _, name := range names {
-		var dummy string
-		err := conn.QueryRow(`SELECT name FROM schema_migrations WHERE name = ?`, name).Scan(&dummy)
-		if err == nil {
-			continue // already applied
+	// Fetch every applied migration name in ONE query rather than one round-trip
+	// per migration. On a high-latency remote MySQL those 20+ SELECTs dominated the
+	// connect time (each RTT × migration count) — the whole logbook connect could
+	// take tens of seconds. One SELECT + an in-memory set is effectively instant.
+	applied := map[string]bool{}
+	if rows, err := conn.Query(`SELECT name FROM schema_migrations`); err == nil {
+		for rows.Next() {
+			var n string
+			if rows.Scan(&n) == nil {
+				applied[n] = true
+			}
 		}
-		if err != sql.ErrNoRows {
-			return fmt.Errorf("check migration %s: %w", name, err)
+		rows.Close()
+	} else {
+		return fmt.Errorf("read applied migrations: %w", err)
+	}
+
+	for _, name := range names {
+		if applied[name] {
+			continue // already applied
 		}
 		content, err := migrationsFS.ReadFile("migrations/" + name)
 		if err != nil {