Session resource grid: no way to reach sessions beyond the 100-session cap

Follow-up from the FR-3571 stack review.

The grid renders at most 100 sessions of the current filter and shows a truncation banner beyond that. There is no pagination or "load more", so the only way to reach the rest is to narrow the filter — which is awkward on the admin page, where more than 100 sessions is normal.

Per Jongeun Lee this was deliberate: the grid still runs on the legacy (non-V2) `compute_session_list` query, so the request is already heavy and auto-refresh would multiply the cost. Lifting the cap depends on migrating the grid to the V2 session connection, which needs schema changes requested from the core team.

**Blocked on**: V2 migration of the session query used by the grid.

Reported by Sujin Kim.

JIRA Issue: FR-3584

Start by tracing the admin session grid and the legacy compute_session_list query mentioned in the issue, then review the V2 session connection and schema changes requested from the core team. Done means sessions beyond the 100-session cap are reachable without narrowing the filter, with the truncation behavior handled appropriately.

Written by the indexing model from the issue text.