Stage 1: project setup, Exercise Library, both Mode designs and the Mode switch

- Flutter Android app on CookIT's stack (provider, shared_preferences, gen-l10n)
- tools/exercise-import turns free-exercise-db into 876 bundled Exercises
  with 1,746 WebP images (20 MB); stretching -> Stretching, rest -> Workout
- ZenStyle tokens per Mode: calm rounded sage/teal with breath ripples vs.
  dark ember-to-red with floor-tape slashes; the theme morphs at each
  Mode's own pace
- Remembered global Mode switch, Plans / Library / History tabs

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/src/exercises/views/library_view.dart

@@ -0,0 +1,108 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../../design/page_header.dart';
+import '../../design/zen_nav_bar.dart';
+import '../../design/zen_style.dart';
+import '../../localization/app_localizations.dart';
+import '../../settings/settings_controller.dart';
+import '../exercise.dart';
+import '../exercise_labels.dart';
+import '../exercise_library.dart';
+
+/// The current Mode's Exercises, by name.
+class LibraryView extends StatelessWidget {
+  const LibraryView({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = AppLocalizations.of(context);
+    final mode = context.watch<SettingsController>().mode;
+    final exercises = context.read<ExerciseLibrary>().forMode(mode);
+    final bottomInset = MediaQuery.paddingOf(context).bottom;
+    return ListView.builder(
+      key: PageStorageKey('library-${mode.name}'),
+      padding: EdgeInsets.only(bottom: ZenNavBar.height + 32 + bottomInset),
+      itemCount: exercises.length + 1,
+      itemBuilder: (context, i) => i == 0
+          ? PageHeader(title: l10n.libraryTitle, subtitle: l10n.librarySubtitle(mode.name, exercises.length))
+          : Padding(
+              padding: const EdgeInsets.fromLTRB(16, 0, 16, 10),
+              child: ExerciseTile(exercise: exercises[i - 1]),
+            ),
+    );
+  }
+}
+
+class ExerciseTile extends StatelessWidget {
+  const ExerciseTile({super.key, required this.exercise, this.onTap});
+
+  final Exercise exercise;
+  final VoidCallback? onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    final s = ZenStyle.of(context);
+    final text = Theme.of(context).textTheme;
+    final muscles = exercise.primaryMuscles.map(sentenceCase).join(', ');
+    return Card(
+      child: InkWell(
+        onTap: onTap,
+        child: Padding(
+          padding: const EdgeInsets.all(10),
+          child: Row(
+            children: [
+              ExerciseThumbnail(exercise: exercise, size: 64),
+              const SizedBox(width: 14),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(exercise.name, style: text.titleMedium, maxLines: 2, overflow: TextOverflow.ellipsis),
+                    const SizedBox(height: 4),
+                    Text(
+                      '$muscles  ·  ${sentenceCase(exercise.level)}',
+                      style: text.bodySmall?.copyWith(color: s.inkMuted),
+                      maxLines: 1,
+                      overflow: TextOverflow.ellipsis,
+                    ),
+                  ],
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+/// The start image in a soft well, or an icon for the few Exercises without images.
+class ExerciseThumbnail extends StatelessWidget {
+  const ExerciseThumbnail({super.key, required this.exercise, required this.size});
+
+  final Exercise exercise;
+  final double size;
+
+  @override
+  Widget build(BuildContext context) {
+    final s = ZenStyle.of(context);
+    final ratio = MediaQuery.devicePixelRatioOf(context);
+    return ClipRRect(
+      borderRadius: BorderRadius.circular((s.radius * 0.6).clamp(0, size / 2)),
+      child: Container(
+        width: size,
+        height: size,
+        color: s.surfaceSoft,
+        child: exercise.images.isEmpty
+            ? Icon(Icons.image_not_supported_outlined, color: s.inkMuted)
+            : Image.asset(
+                exercise.images.first,
+                fit: BoxFit.cover,
+                cacheWidth: (size * ratio).round(),
+                errorBuilder: (_, _, _) => Icon(Icons.image_not_supported_outlined, color: s.inkMuted),
+              ),
+      ),
+    );
+  }
+}