fix(updater): self-register SilverDROID in installed_apps before update check

The worker exited early when the DB was empty (fresh installs via browser).
Now upserts a self-record for slug='silverdroid' before the isEmpty guard
so update notifications fire even when no other apps have been installed
via the AppStore.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/src/main/kotlin/uk/silverlabs/silverdroid/update/UpdateCheckerWorker.kt

@@ -49,6 +49,21 @@ class UpdateCheckerWorker(
     override suspend fun doWork(): Result = withContext(Dispatchers.IO) {
         try {
             val dao = PwaDatabase.getInstance(context).installedAppDao()
+
+            // Ensure SilverDROID itself is always tracked so it can detect its own updates
+            val selfSlug = "silverdroid"
+            val selfVersion = try {
+                context.packageManager.getPackageInfo(context.packageName, 0).versionName ?: "1.0.0"
+            } catch (e: Exception) { "1.0.0" }
+            if (dao.getBySlug(selfSlug) == null) {
+                dao.insert(InstalledApp(
+                    slug = selfSlug,
+                    packageName = context.packageName,
+                    appName = "SilverDROID",
+                    installedVersion = selfVersion
+                ))
+            }
+
             val installedApps = dao.getAllAppsOnce()
 
             if (installedApps.isEmpty()) return@withContext Result.success()