chore(platform): assets app + config Android/iOS + screenshots

- Icônes app (hdpi/mdpi/xhdpi/xxhdpi/xxxhdpi + iOS AppIcon) régénérées
- Launch screens Android + iOS actualisés
- ios/Runner : Info.plist, LaunchScreen.storyboard, project.pbxproj
- android/gradle.properties, drawables, styles (values + values-night)
- assets/images : branding/logo
- Screenshots Flutter (flutter_01-04.png) + script PowerShell start-emulators

android/app/src/main/res/drawable-night-v21/launch_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
+</layer-list>

android/app/src/main/res/drawable-night/launch_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
+</layer-list>

android/app/src/main/res/drawable-v21/launch_background.xml

@@ -1,12 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="?android:colorBackground" />
-
-    <!-- You can insert your own image assets here -->
-    <!-- <item>
-        <bitmap
-            android:gravity="center"
-            android:src="@mipmap/launch_image" />
-    </item> -->
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
 </layer-list>

android/app/src/main/res/drawable/launch_background.xml

@@ -1,12 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="@android:color/white" />
-
-    <!-- You can insert your own image assets here -->
-    <!-- <item>
-        <bitmap
-            android:gravity="center"
-            android:src="@mipmap/launch_image" />
-    </item> -->
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
 </layer-list>

android/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <background android:drawable="@color/ic_launcher_background"/>
+  <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>

android/app/src/main/res/values-night-v31/styles.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is on -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
+        <item name="android:windowSplashScreenBackground">#0A0D1A</item>
+        <item name="android:windowSplashScreenAnimatedIcon">@drawable/android12splash</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+         
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

android/app/src/main/res/values-night/styles.xml

@@ -5,6 +5,10 @@
         <!-- Show a splash screen on the activity. Automatically removed when
              the Flutter engine draws its first frame -->
         <item name="android:windowBackground">@drawable/launch_background</item>
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
     </style>
     <!-- Theme applied to the Android Window as soon as the process has started.
          This theme determines the color of the Android Window while your

android/app/src/main/res/values-v31/styles.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is off -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
+        <item name="android:windowSplashScreenBackground">#FFFFFF</item>
+        <item name="android:windowSplashScreenAnimatedIcon">@drawable/android12splash</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+         
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

android/app/src/main/res/values/colors.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#FFFFFF</color>
+</resources>

android/app/src/main/res/values/styles.xml

@@ -5,6 +5,10 @@
         <!-- Show a splash screen on the activity. Automatically removed when
              the Flutter engine draws its first frame -->
         <item name="android:windowBackground">@drawable/launch_background</item>
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
     </style>
     <!-- Theme applied to the Android Window as soon as the process has started.
          This theme determines the color of the Android Window while your