v1.0.16: spinning sync icon, colorful icon, ON_CHANGE fix, notification fix

- Sync icon now rotates (CSS-style spin) in StatusPill, StatusBanner,
  and card sync button whenever status is SYNCING
- Launcher icon redesigned: indigo→violet→cyan gradient background,
  upload arrow fades white→sky-blue, download arrow fades white→violet,
  soft glow ring behind arrows
- Fix ON_CHANGE not triggering: FileWatchService.start() now called
  from AddPairViewModel.save() so pairs created with ON_CHANGE
  immediately begin watching without needing a toggle or reboot
- Fix FileWatch notification hidden: IMPORTANCE_MIN → IMPORTANCE_LOW
  so the "Watching N folders" notification shows in the shade

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

app/src/main/kotlin/com/syncflow/worker/FileWatchService.kt

@@ -148,7 +148,7 @@ class FileWatchService : Service() {
         val nm = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
         if (nm.getNotificationChannel(CHANNEL_WATCH) == null) {
             nm.createNotificationChannel(
-                NotificationChannel(CHANNEL_WATCH, "File watching", NotificationManager.IMPORTANCE_MIN).apply {
+                NotificationChannel(CHANNEL_WATCH, "File watching", NotificationManager.IMPORTANCE_LOW).apply {
                     description = "Background service watching folders for changes"
                     setShowBadge(false)
                 }