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>

.claude/guidelines/testing.md

@@ -9,18 +9,61 @@
 | **SvelteKit Web** | Vitest | `vitest.config.ts` | `*.test.ts` |
 | **E2E** | Playwright | `playwright.config.ts` | `e2e/*.spec.ts` |
 
-## Coverage Requirements
+## Coverage
 
-```javascript
-// Target: 80% for all new code
-coverageThresholds: {
-  global: {
+### Running coverage locally
+
+```bash
+# From any Vitest package with a test:coverage script
+pnpm run test:coverage
+
+# Across the whole monorepo (turbo orchestrates)
+pnpm run test:coverage
+```
+
+Each package emits `coverage/` with:
+- `lcov.info` — consumed by CI artifact upload and external tools
+- `coverage-summary.json` — machine-readable totals
+- `lcov-report/` — browsable HTML report
+
+### Vitest config template
+
+Packages that need coverage add this block to `vitest.config.ts` and declare `@vitest/coverage-v8` as a devDep:
+
+```ts
+test: {
+  coverage: {
+    provider: 'v8',
+    reporter: ['text', 'lcov', 'json-summary'],
+    reportsDirectory: './coverage',
+    include: ['src/**/*.{ts,svelte}'],
+    exclude: ['src/**/*.{test,spec}.ts', 'src/**/*.d.ts', 'src/**/index.ts'],
+  },
+},
+```
+
+Add a script:
+
+```json
+"test:coverage": "vitest run --coverage"
+```
+
+### CI
+
+`.github/workflows/ci.yml` runs `pnpm run test:coverage` and uploads `**/coverage/lcov.info` + `coverage-summary.json` as an artifact (14-day retention). The step is currently non-blocking via `continue-on-error: true` — we are establishing a baseline before flipping to a hard-fail gate. Remove that flag once the suite is green on main.
+
+### Targets (aspirational, not yet enforced)
+
+```ts
+// Target once we flip coverage to blocking: 80% for all new code
+coverage: {
+  thresholds: {
+    lines: 80,
     branches: 80,
     functions: 80,
-    lines: 80,
     statements: 80,
   },
-}
+},
 ```
 
 ## Test File Organization