chore(ci): add v8 test coverage tracking (non-blocking baseline)

CI previously ran `pnpm run test || true` — test failures were silently
swallowed with no artifact, so we had no visibility into what was actually
passing across 1,296 test files.

- New `test:coverage` turbo pipeline task + root script; packages that opt
  in by declaring their own `test:coverage` get picked up automatically.
- Wired up three high-value Vitest targets: apps/mana/apps/web (main
  frontend, ~590 tests), shared-ui (Svelte component library), and
  shared-storage (S3 client). Each emits lcov.info + coverage-summary.json
  + browsable HTML.
- apps/mana/apps/web `"test"` was running in watch mode (just `vitest`),
  which hangs under turbo orchestration — changed to `vitest run` and
  added `test:watch` for the interactive case.
- CI uploads coverage artifacts (14-day retention) regardless of whether
  tests passed. `continue-on-error: true` replaces `|| true` so a failed
  suite shows up as a warning annotation on the PR rather than being
  invisible. Flip to a hard gate once main is green for a full week.
- Testing guideline documents the pattern + the template vitest config
  + the planned 80% threshold.
- ESLint flat-config `vitest.config.ts` ignore only matched at the root;
  widened to `**/vitest.config.{ts,js,mjs}` so nested configs don't trip
  the project-service parser.

Coverage baseline produced locally:
  shared-storage:  91.37% lines (6 files, 123 tests)
  shared-ui:        2.87% lines (mostly Svelte components, untested)
  apps/mana/web:    9/59 test files fail — pre-existing, not regression

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/mana/apps/web/package.json

@@ -11,8 +11,10 @@
 		"check:watch": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --watch",
 		"format": "prettier --write .",
 		"lint": "prettier --check . && NODE_OPTIONS=--max-old-space-size=8192 eslint .",
-		"test": "vitest",
+		"test": "vitest run",
+		"test:watch": "vitest",
 		"test:ui": "vitest --ui",
+		"test:coverage": "vitest run --coverage",
 		"test:e2e": "playwright test"
 	},
 	"devDependencies": {

apps/mana/apps/web/vite.config.ts

@@ -104,5 +104,20 @@ export default defineConfig({
 	// crash on `test.afterAll()` because they expect a Playwright runner.
 	test: {
 		exclude: ['**/node_modules/**', '**/dist/**', '**/build/**', 'e2e/**', 'tests/e2e/**'],
+		coverage: {
+			provider: 'v8',
+			reporter: ['text', 'lcov', 'json-summary'],
+			reportsDirectory: './coverage',
+			include: ['src/**/*.{ts,svelte}'],
+			exclude: [
+				'src/**/*.{test,spec}.{ts,js}',
+				'src/**/*.d.ts',
+				'src/**/__tests__/**',
+				'src/**/__mocks__/**',
+				'src/routes/**/+{page,layout,server,error}.{ts,svelte}',
+				'src/app.d.ts',
+				'src/hooks.*.ts',
+			],
+		},
 	},
 });