Stop the slow test packages waiting (closes #263)

- Tests hash passwords at bcrypt.MinCost, set through the
  PasswordCost field of db.Params.
- Test IRC servers check the queue only on broker notification;
  one test keeps the 100 ms fallback poll.
- The stop-timeout test shortens the timeout through a test-only
  setter.
- service and handlers tests build config.Config directly instead
  of through config.New, so they run in parallel: service had run
  serially, and handlers started its servers one at a time.
- Repeated race trials run as parallel subtests.
- Fixed sleeps become waits on the broker.
- A new test covers the relay's failed queue read, which only the
  100 ms poll had reached.

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)

internal/db/db.go

@@ -15,6 +15,7 @@ import (
 	"strings"
 
 	"go.uber.org/fx"
+	"golang.org/x/crypto/bcrypt"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/logger"
 
@@ -39,13 +40,19 @@ type Params struct {
 
 	Logger *logger.Logger
 	Config *config.Config
+
+	// PasswordCost is the bcrypt cost at which SetPassword hashes
+	// a password. The server leaves it unset, which means
+	// bcrypt.DefaultCost. Tests set a lower cost to save time.
+	PasswordCost int `optional:"true"`
 }
 
 // Database manages the SQLite connection and migrations.
 type Database struct {
-	conn   *sql.DB
-	log    *slog.Logger
-	params *Params
+	conn         *sql.DB
+	log          *slog.Logger
+	params       *Params
+	passwordCost int
 }
 
 // New creates a new Database and registers lifecycle hooks.
@@ -53,9 +60,15 @@ func New(
 	lifecycle fx.Lifecycle,
 	params Params,
 ) (*Database, error) {
+	passwordCost := params.PasswordCost
+	if passwordCost == 0 {
+		passwordCost = bcrypt.DefaultCost
+	}
+
 	database := &Database{ //nolint:exhaustruct // conn set in OnStart
-		params: &params,
-		log:    params.Logger.Get(),
+		params:       &params,
+		log:          params.Logger.Get(),
+		passwordCost: passwordCost,
 	}
 
 	database.log.Info("Database instantiated")

internal/db/export_test.go

@@ -8,10 +8,12 @@ import (
 	"testing"
 	"time"
 
+	"golang.org/x/crypto/bcrypt"
 	"sneak.berlin/go/neoirc/internal/dbtest"
 )
 
-// NewTestDatabase creates an in-memory database for testing.
+// NewTestDatabase creates an in-memory database for testing. It
+// hashes passwords at bcrypt.MinCost.
 func NewTestDatabase(tb testing.TB) (*Database, error) {
 	tb.Helper()
 
@@ -23,8 +25,9 @@ func NewTestDatabase(tb testing.TB) (*Database, error) {
 	}
 
 	database := &Database{ //nolint:exhaustruct // test helper, params not needed
-		conn: conn,
-		log:  slog.Default(),
+		conn:         conn,
+		log:          slog.Default(),
+		passwordCost: bcrypt.MinCost,
 	}
 
 	err = database.runMigrations(context.Background())