Stop the slow test packages waiting (closes #263)

The slowest test packages spent their time waiting rather than testing.

db.Params gains an optional PasswordCost (zero means bcrypt.DefaultCost), and the db, ircserver and handlers tests hash at bcrypt.MinCost. A test IRC server's relay checks its queue on broker notification instead of polling. The service and handlers tests build config.Config directly and run in parallel; config exports DefaultTrustedProxies and ParseTrustedProxies for them. Fixed sleeps give way to waits for the event. Production defaults are unchanged.

What still takes time is CPU work under -race or a timeout a test is about.

Model: opus-5-5

internal/db/auth.go

@@ -22,7 +22,7 @@ func (database *Database) SetPassword(
 	password string,
 ) error {
 	hash, err := bcrypt.GenerateFromPassword(
-		[]byte(password), bcrypt.DefaultCost,
+		[]byte(password), database.passwordCost,
 	)
 	if err != nil {
 		return fmt.Errorf("hash password: %w", err)