feat: add race cover image extraction

backend/src/db.ts

@@ -24,6 +24,7 @@ function mockRowFromInsert(sql: string, params: unknown[]): RaceRow {
       distance_km: "0",
       status: null,
       official_url: null,
+      cover_image_url: null,
       start_time: null,
       cluster_schedule: null,
       bib_pickup: null,
@@ -47,6 +48,7 @@ function mockRowFromInsert(sql: string, params: unknown[]): RaceRow {
     distance_km: String(row.distance_km ?? "0"),
     status: row.status != null ? String(row.status) : null,
     official_url: row.official_url != null ? String(row.official_url) : null,
+    cover_image_url: row.cover_image_url != null ? String(row.cover_image_url) : null,
     start_time: row.start_time != null ? String(row.start_time) : null,
     cluster_schedule: row.cluster_schedule != null ? String(row.cluster_schedule) : null,
     bib_pickup: row.bib_pickup != null ? String(row.bib_pickup) : null,
@@ -108,7 +110,19 @@ function createMockPool(): Pool {
       if (!existing) {
         return emptyResult();
       }
+      const setMatch = sql.match(/UPDATE races SET (.+) WHERE id =/);
       const updated = { ...existing, updated_at: new Date() };
+      const setColumns =
+        setMatch?.[1]
+          .split(",")
+          .map((part) => part.trim())
+          .filter((part) => !part.startsWith("updated_at"))
+          .map((part) => part.split("=")[0]?.trim())
+          .filter((col): col is string => Boolean(col)) ?? [];
+
+      setColumns.forEach((col, index) => {
+        (updated as unknown as Record<string, unknown>)[col] = p[index] ?? null;
+      });
       store.set(id, updated);
       return {
         rows: [updated as unknown as T],