Add an `integration-tests:desktop-performance` vitest project (with a 10-minute
timeout and serial file execution) targeting `*.desktop-performance.integration.test.ts`,
plus its runner script and the `test:integration:desktop:performance` npm script.
Add the obsidian-dev-utils/vitest-setup endpoint to the unit-tests setupFiles
(resets shared state on globalThis.__obsidianDevUtils and enables async-operation
tracking each test). Dependencies were already on obsidian-dev-utils 75.0.0.