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

server/db.ts

@@ -8,6 +8,7 @@ export interface Db {
   save(state: GameState): void;
   load(id: string): GameState | null;
   listIds(): string[];
+  delete(id: string): boolean;
   close(): void;
 }
 
@@ -29,6 +30,7 @@ export function openDb(filePath: string): Db {
   );
   const byId = db.prepare('SELECT data FROM games WHERE id = ?');
   const all = db.prepare('SELECT id FROM games ORDER BY updated_at DESC');
+  const del = db.prepare('DELETE FROM games WHERE id = ?');
   return {
     save(state) {
       upsert.run(state.id, JSON.stringify(state), new Date().toISOString());
@@ -45,6 +47,9 @@ export function openDb(filePath: string): Db {
     listIds() {
       return (all.all() as { id: string }[]).map((r) => r.id);
     },
+    delete(id) {
+      return del.run(id).changes > 0;
+    },
     close() {
       db.close();
     },