Keep certificate-directory problems on the station window and leave a hand-edit untouched until Save.

Co-authored-by: Cursor <cursoragent@cursor.com>

station/config_test.go

@@ -446,7 +446,10 @@ func TestInvalidSaveWritesNothingAndDoesNotConnect(t *testing.T) {
 	t.Cleanup(st.Close)
 	ctx, cancel := context.WithCancel(t.Context())
 	defer cancel()
-	go func() { _ = st.Run(ctx) }()
+	go func() {
+		// Run's error is observed through State, which is the station seam.
+		_ = st.Run(ctx)
+	}()
 
 	err = st.Save(station.ConfigForm{
 		Host:           "",
@@ -496,7 +499,10 @@ func TestValidSaveCreatesFileAndConnects(t *testing.T) {
 	t.Cleanup(st.Close)
 	ctx, cancel := context.WithCancel(t.Context())
 	defer cancel()
-	go func() { _ = st.Run(ctx) }()
+	go func() {
+		// Run's error is observed through State, which is the station seam.
+		_ = st.Run(ctx)
+	}()
 
 	err = st.Save(station.ConfigForm{
 		Host:           "  127.0.0.1  ",