Add Hall of Fame team selection for completed runs

After marking a run as completed, a modal prompts the player to select
which Pokemon (up to 6) entered the Hall of Fame. The selection is stored
as hof_encounter_ids on the run, displayed in the victory banner, and
can be edited later. This lays the foundation for scoping genlocke
retireHoF to only the actual HoF team.

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

backend/src/app/schemas/run.py

@@ -15,6 +15,7 @@ class RunUpdate(CamelModel):
     name: str | None = None
     status: str | None = None
     rules: dict | None = None
+    hof_encounter_ids: list[int] | None = None
 
 
 class RunResponse(CamelModel):
@@ -23,6 +24,7 @@ class RunResponse(CamelModel):
     name: str
     status: str
     rules: dict
+    hof_encounter_ids: list[int] | None = None
     started_at: datetime
     completed_at: datetime | None