Migrate Session GraphQL queries to Strawberry V2

## Goal

Migrate session-related GraphQL queries in the WebUI to the Strawberry V2 API and drop the remaining legacy V1 session node usage.

## Background

- The first-phase Strawberry V2 migration (FR-2572, done) covered vfolder and several other domains; session queries still rely on legacy nodes in several places.
- New issues will be created under this epic as work is planned.

## Scope

- Migrate session list/detail queries to V2 equivalents
- Display session creator's keypair in session list during session query V2 migration (FR-2771)
- Remove legacy V1 session node references once all consumers are migrated

## Related

- FR-2572 — completed first-phase Strawberry V2 migration epic
- FR-3183 — umbrella epic for removing legacy V1 GraphQL nodes
- FR-3436 — VFolder-side V2 migration epic

JIRA Issue: FR-3437

Start by locating the WebUI's session list and detail GraphQL queries and all remaining legacy V1 session node references. Compare those consumers with the Strawberry V2 equivalents, include the session creator's keypair in the session list, and verify that no V1 session references remain after migration.

Written by the indexing model from the issue text.