ci: integrate Codecov for coverage reporting

Author: ih0r-d

.github/workflows/codecov.yml

@@ -0,0 +1,29 @@
+name: codecov
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  codecov:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-java@v5
+        with:
+          distribution: 'temurin'
+          java-version: 25
+      - uses: actions/cache@v4
+        with:
+          path: ~/.m2/repository
+          key: maven-${{ hashFiles('**/pom.xml') }}
+      - run: |
+          mvn clean install
+      - name: Upload coverage reports to Codecov
+        uses: codecov/codecov-action@v5
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+        with:
+          files: ./target/site/jacoco/jacoco.xml
+          fail_ci_if_error: false

README.md

@@ -4,6 +4,7 @@
 ![Java](https://img.shields.io/badge/JDK-25%2B-007396?logo=openjdk)
 ![GraalVM](https://img.shields.io/badge/GraalVM-25.x-FF6F00?logo=oracle)
 [![Maven Central](https://img.shields.io/maven-central/v/io.github.ih0r-d/polyglot-adapter.svg?label=maven%20central)](https://central.sonatype.com/artifact/io.github.ih0r-d/polyglot-adapter)
+[![codecov](https://codecov.io/gh/<user>/<repo>/branch/main/graph/badge.svg)](https://codecov.io/gh/ih0r-d/polyglot-adapter)
 ![License](https://img.shields.io/badge/license-Apache--2.0-blue)
 
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