Add APK release flow with R2 redirects and updater support

deployment-live-walkthrough.md

@@ -185,7 +185,34 @@ This avoids extension users hitting endpoints that are not ready.
 
 ---
 
-## 8) Rollback Strategy
+## 8) APK Release (Direct Download)
+
+APK release is independent from site redeploy.
+
+Canonical URLs used by the app updater:
+1. `https://dewemoji.com/downloads/version.json`
+2. `https://dewemoji.com/downloads/dewemoji-latest.apk`
+
+Set these env vars on app server:
+
+```env
+DEWEMOJI_APK_RELEASE_ENABLED=true
+DEWEMOJI_APK_PUBLIC_BASE_URL=https://dewemoji.com/downloads
+DEWEMOJI_R2_PUBLIC_BASE_URL=https://downloads.your-r2-domain.com
+DEWEMOJI_R2_APK_VERSION_KEY=apk/version.json
+DEWEMOJI_R2_APK_LATEST_KEY=apk/dewemoji-latest.apk
+```
+
+Validate redirects:
+
+```bash
+curl -I https://dewemoji.com/downloads/version.json
+curl -I https://dewemoji.com/downloads/dewemoji-latest.apk
+```
+
+---
+
+## 9) Rollback Strategy
 
 If release is broken:
 1. Re-deploy previous known-good git commit.
@@ -198,4 +225,3 @@ php artisan queue:restart
 ```
 
 3. If issue is emoji dataset, use snapshot activation in admin catalog.
-