Security fixes: P0-P2 complete (22 fixes)

P0 (7): Auth-bypass removed, migrations fixed, plugin-upload disabled, RLS FORCE+WITH CHECK, plugin double-registration fixed, persistent volume, domain removed
P1 (11): User/tenant model, Redis centralized, worker separated, transactional outbox, XSS fixed, DMS chunked streaming, permissions unified, password reset, metrics secured, config/docs fixed, cross-tenant FK
P2 (4): Contact model normalized, cross-imports reduced 94%, commands+state machines for contacts/dms/mail/calendar, SPA path-traversal

8 new migrations, 99 unit tests, 13 commands, 8 contracts, 72 files changed

app/plugins/builtins/dms/schemas.py

@@ -34,7 +34,7 @@ class FileMetadataResponse(BaseModel):
     uploaded_by: str
     mime_type: str
     size_bytes: int
-    storage_path: str
+    content_hash: str | None = None
     deleted_at: datetime | None = None
     created_at: datetime | None = None
     updated_at: datetime | None = None