feat: add CI/CD workflows and EAS build config (Sprint 5)

BUILDING.md

@@ -0,0 +1,103 @@
+# Building TerritoryLog with EAS
+
+This document explains how to build TerritoryLog APKs and production bundles using **Expo Application Services (EAS)**.
+
+---
+
+## Prerequisites
+
+### 1. Install EAS CLI
+
+```bash
+npm install -g eas-cli
+```
+
+Verify installation:
+
+```bash
+eas --version
+# Should output >= 12.0.0
+```
+
+### 2. Log in to Expo Account
+
+```bash
+eas login
+```
+
+You will be prompted for your Expo username and password. If you don't have an account, create one at [https://expo.dev](https://expo.dev).
+
+---
+
+## Building
+
+### Preview Build (APK — for internal testing)
+
+This generates a standard `.apk` file that can be installed directly on Android devices without the Play Store.
+
+```bash
+eas build --platform android --profile preview
+```
+
+Once the build completes, EAS will provide a download URL for the APK.
+
+### Production Build (AAB — for Play Store submission)
+
+This generates an `.aab` (Android App Bundle) optimized for Play Store distribution.
+
+```bash
+eas build --platform android --profile production
+```
+
+### Development Build (for local development with Expo Go replacement)
+
+```bash
+eas build --platform android --profile development
+```
+
+---
+
+## About Keystores
+
+> **EAS manages keystores automatically.** On your first build, EAS will generate and securely store a keystore on Expo's servers. You don't need to manually create or manage a keystore. If you need to use an existing keystore, see the [EAS credentials documentation](https://docs.expo.dev/app-signing/managed-credentials/).
+
+---
+
+## CI/CD — Setting Up `EXPO_TOKEN` in Gitea
+
+The CI/CD pipeline in `.gitea/workflows/build.yml` requires an `EXPO_TOKEN` secret to authenticate with EAS without interactive login.
+
+### Steps to set up:
+
+1. **Generate an Expo access token:**
+   - Go to [https://expo.dev/accounts/\[your-username\]/settings/access-tokens](https://expo.dev/accounts/)
+   - Click **"Create Token"**
+   - Name it something like `gitea-ci` and copy the token value
+
+2. **Add the secret to Gitea:**
+   - In this repo, go to **Settings → Actions → Secrets**
+   - Click **"Add Secret"**
+   - Name: `EXPO_TOKEN`
+   - Value: *(paste your token)*
+   - Click **"Save"**
+
+3. The `build.yml` workflow will now authenticate automatically when triggered by a push to `main`.
+
+---
+
+## Build Profiles Summary
+
+| Profile       | Output   | Distribution | Use Case                     |
+|---------------|----------|--------------|------------------------------|
+| `development` | APK      | Internal     | Dev client for local testing |
+| `preview`     | APK      | Internal     | QA / internal testing        |
+| `production`  | AAB      | Play Store   | Public release               |
+
+---
+
+## Useful Links
+
+- [EAS Build documentation](https://docs.expo.dev/build/introduction/)
+- [EAS CLI reference](https://docs.expo.dev/eas-cli/)
+- [Android app signing with EAS](https://docs.expo.dev/app-signing/managed-credentials/)
+- [Expo access tokens](https://docs.expo.dev/accounts/programmatic-access/)