feat: change default build target to riscv64

.devcontainer/Dockerfile

@@ -0,0 +1,8 @@
+From docker.educg.net/cg/os-contest:20250226
+
+RUN apt install -y --no-install-recommends \
+    bison flex libssl-dev bridge-utils dnsmasq sudo iptables
+
+RUN cargo install --git https://github.com/Samuka007/DADK.git --branch kpartx-docker-support
+
+ENTRYPOINT ["tini", "--"]

.devcontainer/devcontainer.json

@@ -1,6 +1,9 @@
 {
     "name": "OSCOMP Container",
-    "image": "docker.educg.net/cg/os-contest:20250226",
+    // "image": "docker.educg.net/cg/os-contest:20250226",
+    "build": {
+        "dockerfile": "Dockerfile"
+    },
     "runArgs": [
         "--privileged"
     ],