Rename CLAUDE.md to AGENTS.md and replace Codecov badge with self-hosted JaCoCo badge

.github/workflows/ci.yml

@@ -33,8 +33,19 @@ jobs:
           name: test-report
           path: gridkit-core/build/reports/tests/test/
 
-      - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v5
+      - name: Generate coverage badge
+        if: github.ref == 'refs/heads/main' && github.event_name == 'push'
+        uses: cicirello/jacoco-badge-generator@v2
         with:
-          files: gridkit-core/build/reports/jacoco/test/jacocoTestReport.xml
-          fail_ci_if_error: false
+          jacoco-csv-file: gridkit-core/build/reports/jacoco/test/jacocoTestReport.csv
+          badges-directory: .github/badges
+          generate-branches-badge: true
+
+      - name: Commit coverage badge
+        if: github.ref == 'refs/heads/main' && github.event_name == 'push'
+        run: |
+          git config --local user.name "github-actions[bot]"
+          git config --local user.email "github-actions[bot]@users.noreply.github.com"
+          git add .github/badges/ || true
+          git diff --cached --quiet || git commit -m "chore: update coverage badge [skip ci]"
+          git push

README.md

@@ -3,7 +3,7 @@
 ![GridKit Logo](GridKit.png)
 
 [![CI](https://github.com/tolikttaaa/GridKit/actions/workflows/ci.yml/badge.svg)](https://github.com/tolikttaaa/GridKit/actions/workflows/ci.yml)
-[![codecov](https://codecov.io/gh/tolikttaaa/GridKit/graph/badge.svg?token=R1E33N9QTK)](https://codecov.io/gh/tolikttaaa/GridKit)
+[![Coverage](.github/badges/jacoco.svg)](gridkit-core/build/reports/jacoco/test/index.html)
 
 A Kotlin library providing a unified abstraction layer for tile-based game boards.
 GridKit supports square, hexagonal, and triangular grid topologies through a single,

gridkit-core/build.gradle.kts

@@ -16,6 +16,7 @@ tasks.jacocoTestReport {
     dependsOn(tasks.test)
     reports {
         xml.required = true
+        csv.required = true
         html.required = true
     }
 }