fix(sync): only upload trip CSVs to Dropbox, not every file in the folder

The background DropboxSyncWorker uploaded every file in the local trips dir
(listFiles { isFile }), so the Export-all-as-ZIP bundle (trips_export.dbb,
".zip" on older builds) that lives in that same folder leaked into the
rider's Dropbox /trips alongside the real trips. Filter to *.csv, matching
what SyncManager already does. Existing stray bundles must be deleted from
Dropbox by hand (the sync is upload-only and never removes remote files).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GHUZZ33sT9FYS6sXiMogJc

Author: eried

app/src/main/java/com/eried/eucplanet/data/sync/DropboxSyncWorker.kt

@@ -48,7 +48,13 @@ class DropboxSyncWorker @AssistedInject constructor(
             Log.w(TAG, "list_folder failed, will retry")
             return Result.retry()
         }
-        val localFiles = tripRepository.getTripsDir().listFiles { f -> f.isFile }
+        // Only trip CSVs belong in the Dropbox /trips folder. The trips dir also
+        // holds transient bundles like "trips_export.dbb" (the Export-all-as-ZIP
+        // share file); without this filter the sync uploaded those too, so a
+        // "trips_export.zip/.dbb" leaked into the rider's Dropbox alongside the
+        // real trips.
+        val localFiles = tripRepository.getTripsDir()
+            .listFiles { f -> f.isFile && f.name.endsWith(".csv", ignoreCase = true) }
             ?.toList().orEmpty()
         var anyFailed = false
         var uploaded = 0