fix(backup): stop orphaned backup work when disabled

Turning automatic backup off only cancelled the periodic work, so a
run-now that kept failing (e.g. its folder was deleted) retried forever
and spammed failure notifications.

- Cancel the immediate "run now" work too when backup is disabled.
- Worker no-ops (no retry) when the toggle is off, so already-queued work
  can't revive itself.
- Reconcile scheduled work against saved settings on every app launch —
  re-arms after a reinstall and clears orphaned work once backup is off.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/java/de/jeanlucmakiola/calendula/CalendulaApp.kt

@@ -1,8 +1,16 @@
 package de.jeanlucmakiola.calendula
 
 import android.app.Application
+import dagger.hilt.android.EntryPointAccessors
 import dagger.hilt.android.HiltAndroidApp
+import de.jeanlucmakiola.calendula.data.backup.BackupScheduler
+import de.jeanlucmakiola.calendula.data.backup.BackupWorker
 import de.jeanlucmakiola.calendula.data.crash.CrashReporter
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
 
 /**
  * Application entry point. Registered as android:name=".CalendulaApp"
@@ -16,5 +24,24 @@ class CalendulaApp : Application() {
         // Install first thing so startup crashes are captured too (privacy-
         // respecting, on-device; the user submits the report by hand).
         CrashReporter.install(this)
+        reconcileAutoBackup()
+    }
+
+    /**
+     * Bring the scheduled auto-backup work back in line with the saved settings
+     * on every launch — re-arms it after a reinstall and, crucially, cancels any
+     * orphaned work once backup has been turned off.
+     */
+    private fun reconcileAutoBackup() {
+        val deps = EntryPointAccessors.fromApplication(this, BackupWorker.Deps::class.java)
+        CoroutineScope(SupervisorJob() + Dispatchers.Default).launch {
+            val prefs = deps.settingsPrefs()
+            BackupScheduler.apply(
+                context = this@CalendulaApp,
+                enabled = prefs.autoBackupEnabled.first(),
+                intervalMinutes = prefs.autoBackupIntervalMinutes.first(),
+                hasFolder = prefs.autoBackupFolderUri.first() != null,
+            )
+        }
     }
 }

app/src/main/java/de/jeanlucmakiola/calendula/data/backup/AutoBackup.kt

@@ -55,6 +55,9 @@ object BackupScheduler {
         val workManager = WorkManager.getInstance(context)
         if (!enabled || !hasFolder) {
             workManager.cancelUniqueWork(WORK_NAME)
+            // Also cancel any pending immediate run — otherwise a failing run-now
+            // keeps retrying after the user has turned backup off.
+            workManager.cancelUniqueWork(WORK_NAME_NOW)
             return
         }
         // WorkManager's own floor is 15 min; the UI floors the user choice at 30.
@@ -106,6 +109,9 @@ class BackupWorker(
     override suspend fun doWork(): Result {
         val deps = EntryPointAccessors.fromApplication(applicationContext, Deps::class.java)
         val prefs = deps.settingsPrefs()
+        // Respect the toggle even for already-queued work: if backup was turned
+        // off, no-op (and don't retry) so a lingering run can't revive itself.
+        if (!prefs.autoBackupEnabled.first()) return Result.success()
         val folder = prefs.autoBackupFolderUri.first()
             ?: return Result.failure() // nothing to write to — leave scheduling to settings
         val now = System.currentTimeMillis()