List the requesting user's active allocations. Returned rows include the on-ledger allocation_cid so the frontend can drive the emergency-withdrawal flow.

Optional asset filter narrows results to a single asset. Pass the user-facing asset name (e.g. CC, USDC); aliasing is handled server-side. Only status='active' rows are returned. The expired field is computed server-side: true when allocation_expiration is non-null and in the past, false otherwise (rows with NULL expiration are treated as never-expires).

Hard cap of 500 rows; no pagination cursor (active allocations per user are bounded).