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>

pubspec.yaml

@@ -0,0 +1,73 @@
+name: zenxercise
+description: "ZenXercise – stretching and workout plans."
+publish_to: 'none'
+version: 0.1.0+1
+
+environment:
+  sdk: ^3.8.1
+
+dependencies:
+  flutter:
+    sdk: flutter
+  flutter_localizations:
+    sdk: flutter
+  intl: ^0.20.2
+  provider: ^6.1.5+1
+  shared_preferences: ^2.5.3
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+  flutter_lints: ^5.0.0
+
+flutter:
+  uses-material-design: true
+  generate: true
+
+  assets:
+    - assets/exercises/
+    - assets/exercises/images/
+
+  fonts:
+    # Stretching Mode
+    - family: Nunito
+      fonts:
+        - asset: assets/fonts/Nunito-600.ttf
+          weight: 600
+        - asset: assets/fonts/Nunito-700.ttf
+          weight: 700
+        - asset: assets/fonts/Nunito-800.ttf
+          weight: 800
+        - asset: assets/fonts/Nunito-900.ttf
+          weight: 900
+    - family: NunitoSans
+      fonts:
+        - asset: assets/fonts/NunitoSans-400.ttf
+          weight: 400
+        - asset: assets/fonts/NunitoSans-600.ttf
+          weight: 600
+        - asset: assets/fonts/NunitoSans-700.ttf
+          weight: 700
+        - asset: assets/fonts/NunitoSans-800.ttf
+          weight: 800
+    # Workout Mode
+    - family: BarlowCondensed
+      fonts:
+        - asset: assets/fonts/BarlowCondensed-Medium.ttf
+          weight: 500
+        - asset: assets/fonts/BarlowCondensed-SemiBold.ttf
+          weight: 600
+        - asset: assets/fonts/BarlowCondensed-Bold.ttf
+          weight: 700
+        - asset: assets/fonts/BarlowCondensed-ExtraBold.ttf
+          weight: 800
+    - family: Barlow
+      fonts:
+        - asset: assets/fonts/Barlow-Regular.ttf
+          weight: 400
+        - asset: assets/fonts/Barlow-Medium.ttf
+          weight: 500
+        - asset: assets/fonts/Barlow-SemiBold.ttf
+          weight: 600
+        - asset: assets/fonts/Barlow-Bold.ttf
+          weight: 700