Add genlocke cumulative graveyard with backend endpoint and UI

Aggregates all fainted encounters across every leg of a genlocke into a
unified graveyard view. Backend serves GET /genlockes/{id}/graveyard with
per-entry leg/game context and summary stats (total deaths, deaths per
leg, deadliest leg). Frontend adds a toggle button on the genlocke detail
page that reveals a filterable/sortable grid of grayscale Pokemon cards.

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

frontend/src/components/index.ts

@@ -3,6 +3,7 @@ export { EncounterMethodBadge } from './EncounterMethodBadge'
 export { EncounterModal } from './EncounterModal'
 export { EndRunModal } from './EndRunModal'
 export { GameCard } from './GameCard'
+export { GenlockeGraveyard } from './GenlockeGraveyard'
 export { HofTeamModal } from './HofTeamModal'
 export { GameGrid } from './GameGrid'
 export { Layout } from './Layout'