Root cause

The sessions view rendered each row's agent name by looking up the session's agent_id in the result of useAgents().

useAgents() calls GET /api/agents, and that endpoint excludes hand-spawned agents by default — see crates/librefang-api/src/routes/agents/lifecycle.rs:617-619 (if !params.include_hands.unwrap_or(false) { agents.retain(|e| !e.is_hand); }).

A session owned by a Hand agent carries that hand agent's agent_id on its row (the list handler at crates/librefang-api/src/routes/tools_sessions.rs:391 returns it verbatim), but because the hand agent was filtered out of the agent map, the lookup at crates/librefang-api/dashboard/src/pages/SessionsPage.tsx missed and the row fell back to the sessions.unknown_agent label instead of showing the Hand agent's real name.

The wrong layer was the frontend lookup: the backend already returns the hand agent (with its correct name) when asked via ?include_hands=true, and it already emits the correct agent_id on each session row, so the authoritative fix is to make the sessions view request hand agents.

The fix

Pass { includeHands: true } to useAgents() in SessionsPage.tsx (the hook already supports this option and listAgents() already maps it to include_hands=true).
The agent map then includes hand agents and the agent_id -> name lookup resolves correctly.
No backend route or payload change, so no Rust integration test is needed; no new user-visible strings, so no locale changes.

Verification

• New crates/librefang-api/dashboard/src/pages/SessionsPage.test.tsx (3 cases):
  • requests the agent list with hand agents included — asserts useAgents is called with { includeHands: true }.
  • renders the hand agent's real name for a hand-owned session — a hand-owned session row shows the Hand agent name, not the unknown fallback.
  • falls back to the unknown-agent label when the agent is missing — regression guard for the pre-fix behaviour.
• pnpm typecheck — clean.
• pnpm lint — 0 errors (the one warning at SessionsPage.tsx:42 is the pre-existing const agents = agentsQuery.data ?? [] react-hooks/exhaustive-deps pattern shared by SkillsPage/WorkflowsPage; not introduced here).
• pnpm build — succeeds.
• pnpm test — 81 files, 797 tests pass (includes the new SessionsPage tests and the existing sessions-hands.test.tsx).
• pnpm test:i18n-parity — all locales in parity.

Closes #6156