Retain monotonic signed actual custody quantity and explicitly known or unknown valuation

Verified non-API-key exact configured service with ledger:securities:bridge required. Only the original exact custodian bridge supplies signed actual physical units, liens and optional actual values/income. Unknown is not zero or par. Authentic mismatches remain exceptions. Same-date refresh requires a strictly later observation timestamp; completed-day basis cannot downgrade. Final close-out requires explicitly zero units, liens and remaining income. All mutations require verified authority even in local mode; customers and API keys are refused. Evidence JSON is strict and bounded at 5 MiB; complete responses are bounded at 16 MiB and never silently truncated.