Disable self-updater for F-Droid builds via IS_FDROID_BUILD flag

Add IS_FDROID_BUILD BuildConfig field (default false). The F-Droid
workflow (create-release.yml) flips it to true via sed before building,
alongside the existing permission removal step. Amber.kt gates the
ZapstoreUpdater instantiation on this flag so F-Droid APKs never
attempt to check for or download updates.

https://claude.ai/code/session_01NmFcCFmEbY7NMradkEU5bv

.github/workflows/create-release.yml

@@ -29,9 +29,10 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-gradle-
 
-      - name: Remove self-update permission for F-Droid build
+      - name: Prepare F-Droid build (no self-update)
         run: |
           sed -i '/android.permission.REQUEST_INSTALL_PACKAGES/d' app/src/main/AndroidManifest.xml
+          sed -i 's/buildConfigField "boolean", "IS_FDROID_BUILD", "false"/buildConfigField "boolean", "IS_FDROID_BUILD", "true"/' app/build.gradle
 
       - name: Build APK
         run: ./gradlew assembleRelease --stacktrace

app/build.gradle

@@ -15,6 +15,8 @@ android {
         versionCode 184
         versionName "6.0.0-pre1"
 
+        buildConfigField "boolean", "IS_FDROID_BUILD", "false"
+
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables {
             useSupportLibrary = true

app/src/main/java/com/greenart7c3/nostrsigner/Amber.kt

@@ -132,7 +132,7 @@ class Amber :
     // This runs on the foreground only
     val profileSubscription = ProfileSubscription(client, this, applicationIOScope)
 
-    val zapstoreUpdater: ZapstoreUpdater? = if (!BuildFlavorChecker.isOfflineFlavor()) {
+    val zapstoreUpdater: ZapstoreUpdater? = if (!BuildFlavorChecker.isOfflineFlavor() && !BuildConfig.IS_FDROID_BUILD) {
         ZapstoreUpdater(client, applicationIOScope)
     } else {
         null