Add pokemon status management with death tracking

Implement status change workflow (alive → dead) with confirmation modal,
death cause recording, and visual status indicators on pokemon cards.
Includes backend migration for death_cause field and graveyard view
on the run dashboard.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/RunEncounters.tsx

@@ -121,7 +121,12 @@ export function RunEncounters() {
 
   const handleUpdate = (data: {
     id: number
-    data: { nickname?: string; status?: EncounterStatus; faintLevel?: number }
+    data: {
+      nickname?: string
+      status?: EncounterStatus
+      faintLevel?: number
+      deathCause?: string
+    }
   }) => {
     updateEncounter.mutate(data, {
       onSuccess: () => {
@@ -225,7 +230,9 @@ export function RunEncounters() {
                       {encounter.nickname ?? encounter.pokemon.name}
                       {encounter.status === 'caught' &&
                         encounter.faintLevel !== null &&
-                        ' (dead)'}
+                        (encounter.deathCause
+                          ? ` — ${encounter.deathCause}`
+                          : ' (dead)')}
                     </span>
                   </div>
                 )}