chore: add vitest project names and fix server config root paths (#26684)

Add `name` to all vitest configs matching CI job buckets (server:unit,
server:medium, cli:unit, web:unit, e2e:server, e2e:maintenance) so they
appear as filterable @tags in the Vitest VSCode extension.

Fix `root` in server vitest configs to use an absolute path derived from
`import.meta.url` instead of `'./'`, which resolved relative to the config
file directory (`server/test/`) rather than `server/`, causing test
discovery to fail in the Vitest VSCode extension.

web/vite.config.ts

@@ -56,6 +56,7 @@ export default defineConfig({
     entries: ['src/**/*.{svelte,ts,html}'],
   },
   test: {
+    name: 'web:unit',
     include: ['src/**/*.{test,spec}.{js,ts}'],
     globals: true,
     environment: 'happy-dom',