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/ircserver/relay.go

@@ -17,7 +17,7 @@ import (
 func (c *Conn) relayMessages(ctx context.Context) {
 	// Use a ticker as a fallback; primary wakeup is via
 	// broker notification.
-	ticker := time.NewTicker(pollInterval)
+	ticker := time.NewTicker(c.pollInterval)
 	defer ticker.Stop()
 
 	for {