build: migrate eslint to v10 flat config and upgrade typescript

Replace .eslintrc.json with eslint.config.js using the new flat config
format required by ESLint 10. Swap @typescript-eslint/eslint-plugin and
@typescript-eslint/parser for the unified typescript-eslint package.
Upgrade TypeScript to 5.9 and @types/node to 25. Apply automatic code
fixes: remove unused catch bindings and preserve error cause in auth
header parsing.

ui/filter-component.ts

@@ -83,7 +83,7 @@ const component: ClosureComponent<Attrs> = (initialVnode) => {
     const list = filterList.map((f, idx) => {
       try {
         return parseFilter(attrs.resource, f);
-      } catch (err) {
+      } catch {
         filterInvalid |= 1 << idx;
       }
       return null;