Restrict transfers to HoF team and prevent blocking starter route

Transfer modal now only appears when a Hall of Fame team is selected,
using the existing hofTeam data instead of the survivors endpoint.
Without a HoF selection, advance proceeds directly with no transfer step.

Transferred encounters are now a separate category: they appear in their
own "Transferred Pokemon" section, don't occupy route slots in the
encounter map, and don't block the route-lock check (excluded via
genlocke_transfers subquery). The run detail endpoint returns
transferEncounterIds so the frontend can distinguish them.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/app/api/runs.py

@@ -105,8 +105,19 @@ async def get_run(run_id: int, session: AsyncSession = Depends(get_session)):
             retired_pokemon_ids=retired_pokemon_ids,
         )
 
+    # Load transfer-target encounter IDs for this run
+    transfer_ids_result = await session.execute(
+        select(GenlockeTransfer.target_encounter_id).where(
+            GenlockeTransfer.target_encounter_id.in_(
+                select(Encounter.id).where(Encounter.run_id == run_id)
+            )
+        )
+    )
+    transfer_encounter_ids = [row[0] for row in transfer_ids_result]
+
     response = RunDetailResponse.model_validate(run)
     response.genlocke = genlocke_context
+    response.transfer_encounter_ids = transfer_encounter_ids
     return response