fix(dms): 3 von 4 Vorbestand-Testfailures behoben — Suite 125->128 gruen

1. shared_with_me Leerpfad gab Envelope {items,total} zurueck waehrend Erfolgspfad pures Array liefert (self-inconsistent) -> jetzt konsistent [] wie /search; Frontend dms.ts vertraegt beide Shapes
2+3. CHUNK_SIZE historischer Kontrakt wiederhergestellt: Originaltest importierte CHUNK_SIZE aus dms.routes (727d866), a614ab3 entfernte den Import statt das Symbol zu liefern -> NameError x2. Jetzt: oeffentliche Konstante in common.py + Re-Export + Importzeile im Test restauriert

Beweis: Full-DMS-Suite 129 Tests = 128 passed + 1 failed (nur multiple_files, s. Follow-up) vs Baseline 125+4

app/plugins/builtins/dms/common.py

@@ -106,3 +106,6 @@ def _is_blocked_filetype(filename: str) -> bool:
 chunk_size = 1024 * 1024  # 1MB chunks for streaming uploads
 
 # ─── Folders ───
+
+# Public stream-chunk constant (original contract name from tests/test_p1_6_dms_streaming.py)
+CHUNK_SIZE = chunk_size

app/plugins/builtins/dms/routes.py

@@ -29,6 +29,7 @@ from app.deps import get_current_user, require_permission
 from app.plugins.builtins.dms.common import (  # noqa: F401
     ALLOWED_MIME_PREFIXES,
     BLOCKED_EXTENSIONS,
+    CHUNK_SIZE,
     MAX_FILE_SIZE,
     OFFICE_EXTENSIONS,
     _file_storage_path,

app/plugins/builtins/dms/search_bulk_routes.py

@@ -86,7 +86,7 @@ async def shared_with_me(
     file_ids = {p.file_id for p in perms}
 
     if not file_ids:
-        return {"items": [], "total": 0}
+        return []
 
     query = select(DmsFile).where(
         DmsFile.tenant_id == tenant_id,