Admin tool: whole-ledger power filtering

Strengthen the admin-gated /transactions firehose with powerful, composable filters over the whole ledger (read-only): by account (id/name), player/owner, firm, amount range, date range, memo text (LIKE), plugin_system/source, and direction/type. Sortable, paginated, with a result count and a CSV/export deep link.

• lib/sql/ledger.ts: extend the query with the new predicates (parameterised; index-aware — lean on the read mirror / bounded windows for big scans).
• app/transactions (+ Toolbar): the filter controls + URL-state.
• Pure DAL + presentation; no business logic in the query layer.
• Note interplay with PAR-159 (SYSTEM-account two-hop collapse) — keep the raw ledger view faithful here (forensic), collapse only where PAR-159 specifies.