Show the neoirc-cli screen without waiting at start-up (closes #226)

Run added the start-up status bar and welcome lines through
SetStatus and AddStatus before it started the tview event loop. Both
wait for that loop, so neoirc-cli stopped before it showed its
screen. They now run on a goroutine, as typed lines do.

Run now passes a new UI to run, which holds the start-up path and
returns its error. TestStartUp calls run with a simulation screen and
fails if the status window does not get the welcome lines within five
seconds.

Model: opus-5-5

internal/cli/app_internal_test.go

@@ -4,8 +4,6 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
-	"slices"
-	"strings"
 	"testing"
 	"time"
 
@@ -361,8 +359,7 @@ func TestLinesKeepOrder(t *testing.T) {
 
 // TestStartUp runs the client's start-up path on a simulation
 // screen. It fails unless the event loop starts and the status
-// window gets two lines: first the one that holds "Welcome to
-// neoirc-cli", then the /connect hint.
+// window gets the welcome lines.
 func TestStartUp(t *testing.T) {
 	t.Parallel()
 
@@ -389,22 +386,16 @@ func TestStartUp(t *testing.T) {
 	})
 
 	// run adds the welcome lines on a goroutine, so the status
-	// window is read until it holds two lines. Each read waits for
+	// window is read until they are there. Each read waits for
 	// the event loop, so the reads run on a goroutine too, which
-	// this test stops waiting for after eventLoopTimeout. The
-	// channel has one slot, so that goroutine can still end.
-	shown := make(chan []string, 1)
+	// this test stops waiting for after eventLoopTimeout.
+	shown := make(chan struct{})
 
 	go func() {
 		for {
-			var lines []string
-
-			ui.app.QueueUpdate(func() {
-				lines = slices.Clone(ui.getOrCreateBuffer("(status)").Lines)
-			})
-
-			if len(lines) == welcomeLines {
-				shown <- lines
+			lines, _ := bufferState(ui, "(status)")
+			if lines == welcomeLines {
+				close(shown)
 
 				return
 			}
@@ -413,22 +404,12 @@ func TestStartUp(t *testing.T) {
 		}
 	}()
 
-	var lines []string
-
 	select {
-	case lines = <-shown:
+	case <-shown:
 	case <-time.After(eventLoopTimeout):
 		t.Fatalf("the status window did not get the welcome lines within %v",
 			eventLoopTimeout)
 	}
-
-	if !strings.Contains(lines[0], "Welcome to neoirc-cli") {
-		t.Errorf("first status line is %q, want the welcome line", lines[0])
-	}
-
-	if !strings.Contains(lines[1], "/connect <server-url>") {
-		t.Errorf("second status line is %q, want the /connect hint", lines[1])
-	}
 }
 
 // TestOwnEventFromOtherClient checks that a message, notice,