docs(mobile-client): add deployment guide for Flutter app

- Cover essential pre-release tasks for Android and iOS
- Include steps for updating package ID/bundle identifier, display name, app icons, and signing configurations
- Provide instructions for building release bundles for both platforms

Author: fulleni

src/content/docs/mobile-client/deployment.mdx

@@ -0,0 +1,99 @@
+---
+title: 'Deployment: Mobile Client'
+description: A guide to building and deploying the Flutter mobile app for Android and iOS.
+---
+
+import { Steps, Tabs, TabItem, Aside } from '@astrojs/starlight/components';
+
+This guide covers the essential pre-release tasks for building and deploying the Flutter News App Mobile Client to the Google Play Store and Apple App Store.
+
+<Aside>
+Before you begin, ensure you have configured the app to connect to your production API server by setting the `appEnvironment` constant in `lib/main.dart` to `AppEnvironment.production`.
+</Aside>
+
+<Tabs>
+<TabItem label="Android">
+<Steps>
+1.  **Update the Package ID**
+
+    The Android package ID is a unique identifier for your app. You must change it from the default.
+    -   Open `android/app/build.gradle`.
+    -   Locate the `applicationId` field and change its value to your own unique ID (e.g., `com.yourcompany.newsapp`).
+
+2.  **Change the App Display Name**
+
+    -   Open `android/app/src/main/AndroidManifest.xml`.
+    -   Find the `android:label` attribute within the `<application>` tag and update its value to your app's name.
+
+3.  **Generate App Icons**
+
+    The project uses the `flutter_launcher_icons` package to generate app icons.
+    -   Replace the placeholder icon file in your project's `assets` folder with your own icon (`1024x1024` recommended).
+    -   Update the `flutter_launcher_icons.yaml` file if your icon has a different name.
+    -   Run the following command to generate the icons:
+        ```bash
+        flutter pub run flutter_launcher_icons
+        ```
+
+4.  **Create a Production Keystore**
+
+    You must sign your Android app with a private key before uploading it to the Play Store.
+    -   Follow the official Android documentation to [generate a new upload key and keystore](https://developer.android.com/studio/publish/app-signing#generate-key).
+    -   Securely store the generated `.jks` file and remember your passwords.
+
+5.  **Configure Gradle for Signing**
+
+    -   Create a file named `android/key.properties` (this file is in `.gitignore` and should not be committed).
+    -   Add your keystore information to this file:
+        ```properties
+        storePassword=YOUR_STORE_PASSWORD
+        keyPassword=YOUR_KEY_PASSWORD
+        keyAlias=YOUR_KEY_ALIAS
+        storeFile=path/to/your/keystore.jks
+        ```
+    -   Open `android/app/build.gradle` and ensure the signing configuration section is set up to read from this `key.properties` file.
+
+6.  **Build the Release Bundle**
+
+    Generate a production-ready Android App Bundle (`.aab`):
+    ```bash
+    flutter build appbundle
+    ```
+    The output file will be located at `build/app/outputs/bundle/release/app-release.aab`. You can now upload this file to the Google Play Console.
+
+</Steps>
+</TabItem>
+<TabItem label="iOS">
+<Steps>
+1.  **Update the Bundle Identifier**
+
+    The iOS bundle identifier is a unique ID for your app.
+    -   Open the project in Xcode (`ios/Runner.xcworkspace`).
+    -   In the Project Navigator, select the `Runner` target.
+    -   Go to the "General" tab and update the "Bundle Identifier" field to your unique ID (e.g., `com.yourcompany.newsapp`).
+
+2.  **Update the Display Name**
+
+    -   In the same "General" tab in Xcode, update the "Display Name" field to your app's name.
+
+3.  **Generate the App Icon Set**
+
+    -   In Xcode, navigate to `Runner/Assets.xcassets` and select `AppIcon`.
+    -   Drag and drop your prepared app icons (`.png` files of various required sizes) into the appropriate slots. You can use an online tool to generate these sizes from a single `1024x1024` image.
+
+4.  **Configure Signing & Capabilities**
+
+    -   In Xcode, go to the "Signing & Capabilities" tab.
+    -   Select your development team and ensure a provisioning profile and signing certificate are correctly configured. This is required for deploying to a real device or the App Store. You will need an active Apple Developer account.
+
+5.  **Build the Release Archive**
+
+    Create a build archive to upload to App Store Connect.
+    ```bash
+    flutter build ipa
+    ```
+    This command will create an `.ipa` file inside the `build/ios/ipa/` directory. You can then upload this archive to App Store Connect using Xcode's Organizer or the Transporter app for testing via TestFlight or submission to the App Store.
+
+</Steps>
+</TabItem>
+</Tabs>