Add clang21 devcontainer

* uses devcontainer dev version

Author: arBmind

.devcontainer/clang17/clang17.Dockerfile .devcontainer/clang21/clang21.Dockerfile.devcontainer/clang17/clang17.Dockerfile renamed to .devcontainer/clang21/clang21.Dockerfile

@@ -1,11 +1,12 @@
-FROM mcr.microsoft.com/devcontainers/base:alpine-3.20
+FROM mcr.microsoft.com/devcontainers/base:dev-alpine3.23
 
 RUN \
   apk add --update --no-cache \
-    clang17 \
+    clang21 \
     libc++-dev \
     cmake \
     ninja \
+    qbs \
     git \
     gdb \
     linux-headers \
@@ -25,5 +26,6 @@ RUN \
   && echo "end" >>/home/vscode/.gdbinit
 
 ENV \
-  CC=/usr/bin/clang \
-  CXX=/usr/bin/clang++
+  PATH="/usr/lib/llvm21/bin:${PATH}" \
+  CC=/usr/bin/clang-21 \
+  CXX=/usr/bin/clang++-21

.devcontainer/clang17/devcontainer.json .devcontainer/clang21/devcontainer.json.devcontainer/clang17/devcontainer.json renamed to .devcontainer/clang21/devcontainer.json

@@ -1,15 +1,16 @@
 {
-	"name": "cocpp19-clang17",
+	"name": "cocpp19-clang21",
 	"build": {
-		"dockerfile": "./clang17.Dockerfile",
+		"dockerfile": "./clang21.Dockerfile",
 		"context": "."
 	},
 	"customizations": {
 		"vscode": {
 			"extensions": [
 				"ms-vscode.cpptools",
 				"ms-vscode.cmake-tools",
-				"ms-python.python"
+				"ms-python.python",
+				"qbs-community.qbs-tools"
 			]
 		}
 	},