fix(documents): normalize UUID to undashed hex in raw SQL quota UPDATE

str(uuid) returns dashed format (xxxx-xxxx-…) which mismatches SQLite's
CHAR(32) storage (undashed hex). Replace with .replace('-', '') so the
WHERE clause matches in both SQLite (tests) and PostgreSQL (production).

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

backend/api/documents.py

@@ -345,7 +345,7 @@ async def confirm_upload(
             "  AND (used_bytes + :delta) <= limit_bytes "
             "RETURNING used_bytes, limit_bytes"
         ),
-        {"delta": size, "uid": str(doc.user_id)},
+        {"delta": size, "uid": str(doc.user_id).replace("-", "")},
     )
     row = result.fetchone()
 
@@ -353,7 +353,7 @@ async def confirm_upload(
         # Quota exceeded — fetch current quota state for the 413 body
         quota_result = await session.execute(
             text("SELECT used_bytes, limit_bytes FROM quotas WHERE user_id = :uid"),
-            {"uid": str(doc.user_id)},
+            {"uid": str(doc.user_id).replace("-", "")},
         )
         q = quota_result.fetchone()
         # Delete the pending Document row and best-effort remove the MinIO object