feat(studio): real install progress in the store dialog and the wizard

Both surfaces showed an indeterminate spinner for the whole install,
because the hub only offered a unary call. They now follow
HubAdmin/InstallModuleStream:

- The store's install dialog shows the phase in plain language, the
  overall percentage, megabytes while the size is known, and a seconds
  counter. The counter is the second, independent signal: it keeps
  running even if the hub goes quiet, which is what tells 'slow' apart
  from 'stuck'.
- The setup wizard shows the same bar per module instead of a spinner
  inside the button.
- New strings in both locales for the phases, the byte line and the
  elapsed counter.

progress_bar_visual_test writes the four waiting states to
build/progress/ in either theme, so the result can be judged without
launching the desktop app. Writing it turned up a real trap worth
recording: awaiting toImage() directly in a widget test leaves the
binding waiting forever - the file passed in six seconds, then sat
there until the ten-minute timeout failed the whole suite.
tester.runAsync() is the fix. Full suite: 186 passed.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

test/progress_bar_visual_test.dart

@@ -0,0 +1,124 @@
+// Renders the progress bar in the states an operator actually meets
+// and writes PNGs to build/progress/, so the visual result can be
+// judged without launching the desktop app and stealing focus.
+//
+// Not a golden comparison: there is no committed reference to diff
+// against. It exists to produce evidence, and to guard that every one
+// of these states renders at all in both themes.
+
+import 'dart:io';
+import 'dart:ui' as ui;
+
+import 'package:chain_studio/theme/theme.dart';
+import 'package:chain_studio/widgets/chain_progress_bar.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+class _Case {
+  final String label;
+  final Widget bar;
+  const _Case(this.label, this.bar);
+}
+
+const _cases = <_Case>[
+  _Case(
+    'Nichts messbar: unbestimmt statt leer',
+    ChainProgressBar(stage: 'Modul wird gesucht'),
+  ),
+  _Case(
+    'Download mit Groesse',
+    ChainProgressBar(
+      value: 0.42,
+      stage: 'Wird heruntergeladen',
+      detail: '5,0 von 12,0 MB',
+    ),
+  ),
+  _Case(
+    'Wert steht, Arbeit laeuft weiter',
+    ChainProgressBar(value: 0.74, stage: 'Wird geprueft und entpackt'),
+  ),
+  _Case(
+    'Fertig: nichts bewegt sich mehr',
+    ChainProgressBar(value: 1.0, busy: false, stage: 'Fertig'),
+  ),
+];
+
+Widget _sheet(ThemeData theme, String title) => MaterialApp(
+  theme: theme,
+  debugShowCheckedModeBanner: false,
+  home: Scaffold(
+    body: RepaintBoundary(
+      key: const ValueKey('sheet'),
+      child: Center(
+        child: SizedBox(
+          width: 520,
+          child: Card(
+            margin: const EdgeInsets.all(24),
+            child: Padding(
+              padding: const EdgeInsets.all(24),
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.stretch,
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  Text(title, style: theme.textTheme.titleMedium),
+                  const SizedBox(height: 20),
+                  for (final c in _cases) ...[
+                    Text(c.label, style: theme.textTheme.labelSmall),
+                    const SizedBox(height: 6),
+                    c.bar,
+                    const SizedBox(height: 22),
+                  ],
+                ],
+              ),
+            ),
+          ),
+        ),
+      ),
+    ),
+  ),
+);
+
+Future<void> _capture(WidgetTester tester, String name) async {
+  final boundary = tester.renderObject<RenderRepaintBoundary>(
+    find.byKey(const ValueKey('sheet')),
+  );
+  // toImage is real asynchronous engine work. Awaiting it directly in a
+  // widget test leaves the binding waiting forever afterwards, which
+  // showed up as this file passing in six seconds and then sitting
+  // there until the ten-minute timeout killed the whole suite.
+  final image = await tester.runAsync(() => boundary.toImage(pixelRatio: 2));
+  if (image == null) return;
+  final bytes = await tester.runAsync(
+    () => image.toByteData(format: ui.ImageByteFormat.png),
+  );
+  final dir = Directory('build/progress')..createSync(recursive: true);
+  File('${dir.path}/$name.png').writeAsBytesSync(bytes!.buffer.asUint8List());
+}
+
+void main() {
+  // One capture per run: a second toImage() in the same test binding
+  // never completes, so the theme comes from the environment and the
+  // sheet is rendered twice from outside:
+  //
+  //   flutter test test/progress_bar_visual_test.dart
+  //   PROGRESS_THEME=dark flutter test test/progress_bar_visual_test.dart
+  testWidgets('renders every waiting state', (tester) async {
+    final dark = Platform.environment['PROGRESS_THEME'] == 'dark';
+    tester.view.physicalSize = const Size(1100, 900);
+    tester.view.devicePixelRatio = 1.0;
+    addTearDown(tester.view.reset);
+
+    await tester.pumpWidget(
+      _sheet(
+        dark ? ChainTheme.dark() : ChainTheme.light(),
+        dark ? 'Dunkel' : 'Hell',
+      ),
+    );
+    // Mid-sweep, so the highlight sits inside the bar in the capture.
+    await tester.pump(const Duration(milliseconds: 900));
+    expect(find.byType(ChainProgressBar), findsNWidgets(_cases.length));
+    await _capture(tester, dark ? 'states-dark' : 'states-light');
+    await tester.pumpWidget(const SizedBox());
+  });
+}