feat: add test coverage reporting with GitHub Pages deployment (#188)

* feat(ci): add test coverage reporting with GitHub Pages deployment

Add coverage script to package.json and update CI workflow to:
- Run CI on all pushes (not just main branch)
- Execute tests with coverage on main branch only
- Upload coverage reports to GitHub Pages for main branch
- Run regular tests without coverage on other branches/PRs

This addresses the need for visibility into test coverage metrics
while keeping PR builds fast by only generating coverage on main.

Closes #184

* chore(deps): upgrade vitest to v4.0.15

Update vitest and @vitest/coverage-v8 from v3.2.4 to v4.0.15.

Vitest v4 introduces several improvements including:
- Stable browser mode
- Visual regression testing support
- Rewritten pool architecture without Tinypool
- Workspace renamed to projects configuration

This upgrade prepares the codebase for using v4's projects feature
for monorepo test aggregation.

Closes #186

* feat(test): configure vitest projects for monorepo coverage

Refactor vitest configuration to use v4's projects feature for
unified monorepo test execution and coverage reporting.

Changes:
- Add projects configuration with 'root' and 'examples' workspaces
- Simplify package.json test scripts (remove test:submodules, test:root)
- Extend coverage.include to capture examples/**/*.ts files
- Enable automatic test discovery in examples when tests are added

This allows running all tests across the monorepo with a single
'pnpm test' command and generates unified coverage reports that
include both src and examples directories.

* chore: update actionss

* feat(ci): add coverage badge generation

Add automatic coverage badge SVG generation using
jaywcjlove/coverage-badges-cli action.

Changes:
- Add json-summary reporter to vitest coverage config
- Generate badges.svg from coverage-summary.json in CI
- Badge will be available at GitHub Pages URL/badges.svg

This enables adding a coverage badge to README that automatically
updates when coverage changes.

* chore(ci): update actions

Update coverage-badges-cli action reference to v2.2.0 with correct SHA.

Author: ryoppippi

.github/workflows/ci.yaml

@@ -1,6 +1,7 @@
 name: CI
 
 on:
+  push:
   pull_request:
     branches:
       - main
@@ -9,6 +10,11 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
 jobs:
   ci:
     runs-on: ubuntu-latest
@@ -32,4 +38,34 @@ jobs:
         run: nix develop --command pnpm run build
 
       - name: Run Tests
+        if: github.ref != 'refs/heads/main'
         run: nix develop --command pnpm test
+
+      - name: Run Tests with Coverage
+        if: github.ref == 'refs/heads/main'
+        run: nix develop --command pnpm run coverage
+
+      - name: Create Coverage Badge
+        if: github.ref == 'refs/heads/main'
+        uses: jaywcjlove/coverage-badges-cli@bd6ccbf422c0ed54c01f283019fd2bc648f58541 # v2.2.0
+        with:
+          source: coverage/coverage-summary.json
+          output: coverage/badges.svg
+
+      - name: Upload coverage artifact
+        if: github.ref == 'refs/heads/main'
+        uses: actions/upload-pages-artifact@7b1f4a764d45c48632c6b24a0339c27f5614fb0b # v4.0.0
+        with:
+          path: coverage
+
+  deploy-coverage:
+    if: github.ref == 'refs/heads/main'
+    needs: ci
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac5b3c0c03e # v4.0.5

package.json

@@ -27,9 +27,8 @@
     "lint:knip": "knip",
     "preinstall": "npx only-allow pnpm",
     "prepack": "npm pkg delete scripts.preinstall && pnpm run build",
-    "test": "pnpm --aggregate-output run '/^test:/'",
-    "test:submodules": "pnpm --parallel -r --aggregate-output test",
-    "test:root": "vitest",
+    "test": "vitest",
+    "coverage": "vitest run --coverage",
     "typecheck": "pnpm --aggregate-output run '/^typecheck:/'",
     "typecheck:submodules": "pnpm --parallel -r --aggregate-output typecheck",
     "typecheck:root": "tsgo --noEmit"