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>

android/settings.gradle.kts

@@ -0,0 +1,25 @@
+pluginManagement {
+    val flutterSdkPath = run {
+        val properties = java.util.Properties()
+        file("local.properties").inputStream().use { properties.load(it) }
+        val flutterSdkPath = properties.getProperty("flutter.sdk")
+        require(flutterSdkPath != null) { "flutter.sdk not set in local.properties" }
+        flutterSdkPath
+    }
+
+    includeBuild("$flutterSdkPath/packages/flutter_tools/gradle")
+
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+plugins {
+    id("dev.flutter.flutter-plugin-loader") version "1.0.0"
+    id("com.android.application") version "8.7.3" apply false
+    id("org.jetbrains.kotlin.android") version "2.1.0" apply false
+}
+
+include(":app")