docs(shire): add diff information to shire-toolchain-variable.md

Update the shire-toolchain-variable documentation by including the new `diff` variable that represents the diff information for the selected commit. Additionally, bump the plugin version from 1.0.6-SNAPSHOT to 1.0.6.

docs/shire/shire-toolchain-variable.md

@@ -25,6 +25,7 @@ Git 工具链提供以下变量：
 - `currentChanges`，当前分支的当前更改。
 - `currentBranch`，当前分支的名称。
 - `historyCommitMessages`，当前提交的提交消息。
+- `diff`，当前选中 commit 的 diff 信息。
 
 ## SonarQube
 

gradle.properties

@@ -6,7 +6,7 @@ pluginGroup = com.phodal.shire
 pluginName = Shire - AI Coding Agent Language
 pluginRepositoryUrl = https://github.com/phodal/shire
 # SemVer format -> https://semver.org
-pluginVersion = 1.0.6-SNAPSHOT
+pluginVersion = 1.0.6
 
 # IntelliJ Platform Properties -> https://plugins.jetbrains.com/docs/intellij/tools-gradle-intellij-plugin.html#configuration-intellij-extension
 platformType = IU