feat: remove a saved game & redirect on missing/deleted game (#20)

- DELETE /api/games/:id route + Db.delete() (404 when absent)
- PresetPicker: per-saved-game trash button + confirm dialog (Cancel/Delete)
- App: runDeleteGame; useSse onError -> goHome on 'deleted'/'not found'
  (a deleted/missing game now returns the live tab and any deep link home)
- DeleteGameResponse in shared/protocol.ts; api.deleteGame()
- unit test (Db.delete) + 2 e2e tests (home-screen delete; in-flight delete
  returns the active tab home and a fresh deep link lands on home)
- version 0.7.0 -> 0.8.0 + changelog

Fixes #20

src/lib/sse.ts

@@ -5,6 +5,12 @@ import type { TurnResult } from '@shared/protocol';
 interface SseHandlers {
   onState?: (state: GameState) => void;
   onTurn?: (state: GameState, result: TurnResult) => void;
+  /**
+   * Fired for a server-sent NAMED `event: error` (a MessageEvent with a JSON
+   * body `{ message }`) — e.g. the game was deleted or no longer exists. Pure
+   * connection errors (no data) are ignored and EventSource auto-reconnects.
+   */
+  onError?: (message: string) => void;
 }
 
 /**
@@ -37,8 +43,19 @@ export function useSse(id: string | null, handlers: SseHandlers): void {
         /* ignore malformed */
       }
     };
+    const onError = (e: Event) => {
+      if (e instanceof MessageEvent && e.data) {
+        try {
+          const d = JSON.parse(e.data) as { message?: string };
+          if (d.message) handlersRef.current.onError?.(d.message);
+        } catch {
+          /* ignore malformed */
+        }
+      }
+    };
     es.addEventListener('state', onState);
     es.addEventListener('turn', onTurn);
+    es.addEventListener('error', onError);
     return () => es.close();
   }, [id]);
 }