feat: l goes to the details of what's selected; enter still drills in

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/ui/app/app_test.go

@@ -758,7 +758,9 @@ func TestFocusKeys(t *testing.T) {
 	}{
 		{"tab", paneContainers}, {"enter", paneSecrets}, {"enter", paneDetail},
 		{"enter", paneDetail}, {"esc", paneSecrets}, {"shift+tab", paneContainers},
-		{"4", paneDetail}, {"l", paneSources}, {"h", paneDetail},
+		{"4", paneDetail}, {"tab", paneSources}, {"shift+tab", paneDetail},
+		// l: what's selected, on the right; h: back to it.
+		{"2", paneContainers}, {"l", paneDetail}, {"h", paneContainers}, {"h", paneSources}, {"l", paneDetail},
 	} {
 		d.keys(tc.key)
 		if d.m.focus != tc.want {