feat: integrate Codecov coverage reporting for monorepo

Add coverage collection to CI test steps (backend, frontend, plugin)
and upload reports to Codecov with per-workspace flags. Add codecov.yml
with flag-based path mappings and carryforward support.

Author: brunobuddy

.github/workflows/ci.yml

@@ -46,8 +46,16 @@ jobs:
       - run: npm run build --workspace=packages/backend
       - name: Test migrations
         run: npm run migration:run --workspace=packages/backend
-      - run: npm test --workspace=packages/backend
-      - run: npm run test:e2e --workspace=packages/backend
+      - run: npm test --workspace=packages/backend -- --coverage --coverageReporters=lcov
+      - run: npm run test:e2e --workspace=packages/backend -- --coverage --coverageReporters=lcov
+      - name: Upload backend coverage to Codecov
+        if: always()
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          flags: backend
+          directory: packages/backend
+          fail_ci_if_error: false
 
   backend-sqlite:
     name: Backend (SQLite)
@@ -82,9 +90,17 @@ jobs:
       - run: npm ci
       - run: npx tsc --noEmit
         working-directory: packages/frontend
-      - run: npm test --workspace=packages/frontend
+      - run: npm test --workspace=packages/frontend -- --coverage
       - run: npx vite build
         working-directory: packages/frontend
+      - name: Upload frontend coverage to Codecov
+        if: always()
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          flags: frontend
+          directory: packages/frontend/coverage
+          fail_ci_if_error: false
 
   plugin:
     runs-on: ubuntu-latest
@@ -95,7 +111,15 @@ jobs:
           node-version: 22
           cache: npm
       - run: npm ci
-      - run: npm test --workspace=packages/openclaw-plugin
+      - run: npm test --workspace=packages/openclaw-plugin -- --coverage --coverageReporters=lcov
+      - name: Upload plugin coverage to Codecov
+        if: always()
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          flags: plugin
+          directory: packages/openclaw-plugin
+          fail_ci_if_error: false
 
   changeset-check:
     name: Changeset status

codecov.yml

@@ -0,0 +1,23 @@
+coverage:
+  status:
+    project:
+      default:
+        target: auto
+    patch:
+      default:
+        target: auto
+flags:
+  backend:
+    paths:
+      - packages/backend/src/
+    carryforward: true
+  frontend:
+    paths:
+      - packages/frontend/src/
+    carryforward: true
+  plugin:
+    paths:
+      - packages/openclaw-plugin/src/
+    carryforward: true
+comment:
+  layout: "reach,diff,flags"