fix: add edit button, bypass constraints on manual sync

- Add Edit icon to PairDetailScreen top bar
- Wire onEdit callback through NavGraph to AddPairScreen with pairId
- Manual "Sync now" (home card + detail screen) now ignores wifiOnly
  and chargingOnly constraints so it runs immediately on tap

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

app/src/main/kotlin/com/syncflow/ui/navigation/NavGraph.kt

@@ -48,6 +48,7 @@ fun SyncFlowNavGraph(navController: NavHostController) {
         ) {
             PairDetailScreen(
                 onBack = { navController.popBackStack() },
+                onEdit = { id -> navController.navigate(Screen.AddPair.route(id)) },
                 onConflicts = { id -> navController.navigate(Screen.Conflicts.route(id)) },
             )
         }