feat(ci): Add basic CI workflow with three build steps

Introduce a basic CI pipeline configuration using GitHub Actions. The
workflow runs on Ubuntu and consists of three simple build steps, which
print progress messages. This setup will serve as a foundation for
future CI/CD enhancements.

.gitea/workflows/ci.yml

@@ -0,0 +1,18 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Step one
+        run: echo "Step one passed"
+
+      - name: Step two
+        run: echo "Step two passed"
+
+      - name: Step three
+        run: echo "Step three passed"