v3: allow users to edit dump thumbnail, fixed some linter errors in the frontend

api/db/migrations/0002_dump_thumbnail.ts

@@ -0,0 +1,14 @@
+import type { DatabaseSync } from "node:sqlite";
+
+// Idempotent: safe to run against a fresh db (already created from schema.sql
+// with this column) or an existing one that predates it.
+export function up(db: DatabaseSync): void {
+  const dumpCols = db.prepare(`PRAGMA table_info(dumps);`).all() as {
+    name: string;
+  }[];
+  if (!dumpCols.some((c) => c.name === "custom_thumbnail_mime")) {
+    db.exec(
+      `ALTER TABLE dumps ADD COLUMN custom_thumbnail_mime TEXT;`,
+    );
+  }
+}