Feature: Add devcontainer support for plugin development

.devcontainer/Dockerfile

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+FROM ubuntu:22.04
+
+# Prevent interactive prompts during package installation
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install required packages
+RUN apt-get update && apt-get install -y \
+    coreutils \
+    bash \
+    openjdk-17-jdk \
+    unzip \
+    wget \
+    git \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Gradle manually
+ENV GRADLE_VERSION=8.1
+RUN wget https://services.gradle.org/distributions/gradle-${GRADLE_VERSION}-bin.zip && \
+    unzip gradle-${GRADLE_VERSION}-bin.zip -d /opt && \
+    ln -s /opt/gradle-${GRADLE_VERSION}/bin/gradle /usr/local/bin/gradle && \
+    rm gradle-${GRADLE_VERSION}-bin.zip
+
+# Set up environment variables
+ENV JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
+ENV GRADLE_HOME=/opt/gradle-8.1
+ENV PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:${JAVA_HOME}/bin:${GRADLE_HOME}/bin
+
+# Create a non-root user
+RUN useradd -ms /bin/bash devuser
+USER devuser
+WORKDIR /workspaces
+
+# Verify essential commands are in path
+SHELL ["/bin/bash", "-c"]
+RUN echo $PATH && \
+    which sleep && \
+    which java && \
+    which gradle

.devcontainer/devcontainer.json

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+{
+  "name": "KCL IntelliJ Dev Container",
+  "build": {
+    "dockerfile": "Dockerfile",
+    "context": "."
+  },
+  "remoteUser": "devuser",
+  "workspaceMount": "source=${localWorkspaceFolder},target=/workspaces/${localWorkspaceFolderBasename},type=bind",
+  "workspaceFolder": "/workspaces/${localWorkspaceFolderBasename}",
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "vscjava.vscode-java-pack",
+        "vscjava.vscode-gradle",
+        "redhat.java",
+        "vscjava.vscode-maven",
+        "vscjava.vscode-java-debug",
+        "vscjava.vscode-java-test"
+      ],
+      "settings": {
+        "java.jdt.ls.java.home": "/usr/lib/jvm/java-17-openjdk-amd64",
+        "java.configuration.runtimes": [
+          {
+            "name": "JavaSE-17",
+            "path": "/usr/lib/jvm/java-17-openjdk-amd64",
+            "default": true
+          }
+        ],
+        "terminal.integrated.shell.linux": "/bin/bash",
+        "terminal.integrated.defaultProfile.linux": "bash"
+      }
+    }
+  },
+  "remoteEnv": {
+    "JAVA_HOME": "/usr/lib/jvm/java-17-openjdk-amd64",
+    "GRADLE_HOME": "/opt/gradle-8.1",
+    "PATH": "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:${JAVA_HOME}/bin:${GRADLE_HOME}/bin:${PATH}"
+  },
+  "postStartCommand": "echo 'Container started successfully'"
+}