e27af75e21
Installs @vitest/coverage-v8 and configures coverage measurement over src/lib/utils/** and src/lib/server/** — the utility and server-side logic that is meaningful to measure in the Node test project. Svelte component files and generated code (api/**, paraglide/**) are excluded; those run in the browser project. Baseline: 87.87% branch coverage — already above the 80% threshold. Adds test:coverage script for local runs; produces lcov report for CI. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>