Initialize Harmness Browser JetBrains plugin skeleton

- Gradle + Kotlin + IntelliJ Platform SDK build
- JCEF embedded browser tool window with configurable start URL
- Settings page (Tools > Harmness Browser)
- JS<->Java bridge scaffold (window.harmnessBridge)
- Vite + React + TypeScript web scaffold for embedded page
- README: build, register, upload to Marketplace, install guide

scripts/setup-toolchain.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# 准备本地构建工具链（无 root 安装，全部放到工作区 .tools 下）
+set -euo pipefail
+
+TOOLS_DIR="/data/project/Plugin/harmness/.tools"
+mkdir -p "$TOOLS_DIR"
+cd "$TOOLS_DIR"
+
+JDK_VERSION="jdk-17.0.12+7"
+GRADLE_VERSION="gradle-8.11.1"
+
+echo "==> Downloading Temurin JDK17 ..."
+curl -fL --retry 3 -o jdk17.tar.gz \
+  "https://github.com/adoptium/temurin17-binaries/releases/download/${JDK_VERSION}/OpenJDK17U-jdk_x64_linux_hotspot_17.0.12_7.tar.gz"
+tar xzf jdk17.tar.gz
+chmod +x jdk-17.0.12+7/bin/java
+"$TOOLS_DIR/jdk-17.0.12+7/bin/java" -version
+
+echo "==> Downloading Gradle $GRADLE_VERSION ..."
+curl -fL --retry 3 -o gradle.zip \
+  "https://services.gradle.org/distributions/${GRADLE_VERSION}-bin.zip"
+unzip -q gradle.zip
+chmod +x "$GRADLE_VERSION/bin/gradle"
+JAVA_HOME="$TOOLS_DIR/jdk-17.0.12+7" "$GRADLE_VERSION/bin/gradle" --version
+
+echo "==> DONE"