feat: add Codecov upload workflows for backend and frontend coverage

.github/workflows/codecov-upload.yml

@@ -0,0 +1,77 @@
+name: Upload Coverage to Codecov (Push only)
+
+on:
+  push:
+    branches:
+      - main
+      - development
+      - 'feature/**'
+
+permissions:
+  contents: read
+
+jobs:
+  backend-codecov:
+    name: Backend Codecov Upload
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.25.4'
+          cache-dependency-path: backend/go.sum
+
+      - name: Run Go tests
+        working-directory: backend
+        env:
+          CGO_ENABLED: 1
+        run: |
+          go test -race -v -coverprofile=coverage.out ./... 2>&1 | tee test-output.txt
+          exit ${PIPESTATUS[0]}
+
+      - name: Upload backend coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          files: ./backend/coverage.out
+          flags: backend
+          fail_ci_if_error: true
+
+  frontend-codecov:
+    name: Frontend Codecov Upload
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '24.11.1'
+          cache: 'npm'
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Install dependencies
+        working-directory: frontend
+        run: npm ci
+
+      - name: Run frontend tests and coverage
+        working-directory: ${{ github.workspace }}
+        run: |
+          bash scripts/frontend-test-coverage.sh 2>&1 | tee frontend/test-output.txt
+          exit ${PIPESTATUS[0]}
+
+      - name: Upload frontend coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          directory: ./frontend/coverage
+          flags: frontend
+          fail_ci_if_error: true