build(devcontainer): 🏗️ add devcontainer files

.devcontainer/devcontainer-lock.json

@@ -0,0 +1,19 @@
+{
+  "features": {
+    "ghcr.io/devcontainers-contrib/features/dprint-asdf:2": {
+      "version": "2.0.14",
+      "resolved": "ghcr.io/devcontainers-contrib/features/dprint-asdf@sha256:056ad0c43ded376371c6a80d6067453a37316adaf03f9e467a09ecba7c13669e",
+      "integrity": "sha256:056ad0c43ded376371c6a80d6067453a37316adaf03f9e467a09ecba7c13669e"
+    },
+    "ghcr.io/devcontainers-contrib/features/protoc:1": {
+      "version": "1.0.2",
+      "resolved": "ghcr.io/devcontainers-contrib/features/protoc@sha256:436d25961d1c3bbc39a565c004d0eca8dd9c0cb80c0319d089d0aa49dc2ad070",
+      "integrity": "sha256:436d25961d1c3bbc39a565c004d0eca8dd9c0cb80c0319d089d0aa49dc2ad070"
+    },
+    "ghcr.io/marcozac/devcontainer-features/buf:1": {
+      "version": "1.0.0",
+      "resolved": "ghcr.io/marcozac/devcontainer-features/buf@sha256:a7ce65c9ab101ea5d0f5378e49c260df1d3123171d3219cd2060163d6406dd26",
+      "integrity": "sha256:a7ce65c9ab101ea5d0f5378e49c260df1d3123171d3219cd2060163d6406dd26"
+    }
+  }
+}

.devcontainer/devcontainer.json

@@ -0,0 +1,11 @@
+{
+  "name": "Rust",
+  "image": "mcr.microsoft.com/devcontainers/rust:1-1-bookworm",
+  "features": {
+    "ghcr.io/devcontainers-contrib/features/protoc:1": {},
+    "ghcr.io/marcozac/devcontainer-features/buf:1": {},
+    "ghcr.io/devcontainers-contrib/features/dprint-asdf:2": {}
+  },
+  "containerUser": "vscode",
+  "remoteUser": "vscode"
+}

.github/dependabot.yml

@@ -0,0 +1,12 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for more information:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+# https://containers.dev/guide/dependabot
+
+version: 2
+updates:
+ - package-ecosystem: "devcontainers"
+   directory: "/"
+   schedule:
+     interval: weekly

.vscode/settings.json

@@ -3,6 +3,7 @@
     "actions",
     "config",
     "deps",
+    "devcontainer",
     "packaging",
     "rsjudge-grpc",
     "rsjudge-judger",