test(e2e): webdav + nextcloud full e2e test coverage

add a full coverage of Webdav and Nextcloud
    purpose: prepare move to Drives and ensure no regression at all

    test scenarios are in docs/plan/BASELINE_TESTS_NC_WEBDAV.md

    current existing bugs identified via these tests:

      ┌──────────┬─────────┬────────────────────────────────────────────────────────────────────────────────────────────────────┐
      │   Bug    │ Surface │                                            Pin location                                            │
      ├──────────┼─────────┼────────────────────────────────────────────────────────────────────────────────────────────────────┤
      │ G4/G5/K5 │ NC      │ AlreadyExists → 500 instead of 412 (handle_move + trashbin restore)                                │
      ├──────────┼─────────┼────────────────────────────────────────────────────────────────────────────────────────────────────┤
      │ G9       │ NC      │ Folder DELETE not row-recursive — orphan descendants stay live                                     │
      ├──────────┼─────────┼────────────────────────────────────────────────────────────────────────────────────────────────────┤
      │ M5/M7    │ Native  │ resolve_path_for_user mismatch — PUT writes, GET reads via lenient lookup, MOVE/DELETE can't find  │
      │          │         │ via strict                                                                                         │
      ├──────────┼─────────┼────────────────────────────────────────────────────────────────────────────────────────────────────┤
      │ M8       │ Native  │ COPY discards destination filename — collides with source                                          │
      ├──────────┼─────────┼────────────────────────────────────────────────────────────────────────────────────────────────────┤
      │ N2       │ Native  │ LOCK creates the token, mutators don't check it — class-2 advertisement is aspirational            │
      └──────────┴─────────┴────────────────────────────────────────────────────────────────────────────────────────────────────┘

tests/api/storage_cleanup_check.sh

@@ -151,6 +151,26 @@ log "API confirms trash is empty."
 THUMB_FILES=$(find "$STORAGE_PATH/.thumbnails" -type f 2>/dev/null || true)
 BLOB_FILES=$(find  "$STORAGE_PATH/.blobs"      -type f 2>/dev/null || true)
 
+# Chunked-upload spool. After every chunked-upload session is either
+# completed (assembled + promoted) or aborted, this dir MUST be empty
+# — a leftover chunk file means a session-cleanup path forgot its
+# `remove_dir_all`, which under sustained sync workloads is the
+# classic "disk fills up over the weekend" failure mode.
+#
+# `.uploads/` is the default chunked-upload root when
+# `OXICLOUD_CHUNK_DIR` is unset (see `common/di.rs`). REST sessions
+# land under `.uploads/<session_id>/`; NC sessions land under
+# `.uploads/nextcloud/<user>/<session_id>/`.
+#
+# We deliberately do NOT check the direct-PUT spool dir here: when
+# `OXICLOUD_UPLOAD_TEMP_DIR` is unset (the default in the test env)
+# it falls back to the OS temp dir (`/tmp/…`) which is shared with
+# the rest of the system and would produce false positives. To
+# extend the check to direct-PUT, set OXICLOUD_UPLOAD_TEMP_DIR in
+# tests/common/server.env to a path under $STORAGE_PATH and add it
+# to the find list below.
+UPLOAD_FILES=$(find "$STORAGE_PATH/.uploads"  -type f 2>/dev/null || true)
+
 if [[ -n "$THUMB_FILES" ]]; then
     THUMB_COUNT=$(echo "$THUMB_FILES" | wc -l | tr -d ' ')
     log "Leftover thumbnail files ($THUMB_COUNT):"
@@ -165,4 +185,11 @@ if [[ -n "$BLOB_FILES" ]]; then
     fail "$BLOB_COUNT blob file(s) remain on disk after full cleanup"
 fi
 
-log "OK — no blobs or thumbnails remain on disk."
+if [[ -n "$UPLOAD_FILES" ]]; then
+    UPLOAD_COUNT=$(echo "$UPLOAD_FILES" | wc -l | tr -d ' ')
+    log "Leftover chunked-upload files ($UPLOAD_COUNT):"
+    echo "$UPLOAD_FILES"
+    fail "$UPLOAD_COUNT chunked-upload file(s) remain in .uploads after full cleanup"
+fi
+
+log "OK — no blobs, thumbnails, or chunked-upload leftovers remain on disk."