feat: add self-contained gitea runner dockerfile with all build tools included

docker/runner/entrypoint.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+set -e
+
+# If GITEA_INSTANCE_URL and GITEA_RUNNER_TOKEN are provided, try to register
+if [ -n "$GITEA_INSTANCE_URL" ] && [ -n "$GITEA_RUNNER_TOKEN" ]; then
+    if [ ! -f ".runner" ]; then
+        echo "Registering runner..."
+        act_runner register \
+          --instance "$GITEA_INSTANCE_URL" \
+          --token "$GITEA_RUNNER_TOKEN" \
+          --name "custom-mips-runner-$(hostname)" \
+          --no-interactive
+    else
+        echo "Runner already registered."
+    fi
+fi
+
+# Run the daemon
+echo "Starting act_runner daemon..."
+exec act_runner daemon