Add AAAxisTitle model for axis title options

Introduces AAAxisTitle class and AAChartAxisTitleAlignValueType enum to represent axis title configuration options for charts, including alignment, margin, offset, rotation, style, text, and HTML rendering support.

Author: AAChartModel

charts/src/main/java/com/github/aachartmodel/aainfographics/aaoptionsmodel/AAAxisTitle.kt

@@ -0,0 +1,76 @@
+package com.github.aachartmodel.aainfographics.aaoptionsmodel
+
+import com.github.aachartmodel.aainfographics.aachartcreator.AAChartAlignType
+
+// https://api.highcharts.com/highcharts/xAxis.title.align
+// https://api.highcharts.com/highcharts/yAxis.title.align
+enum class AAChartAxisTitleAlignValueType(val value: String) {
+    High("high"),
+    Low("low"),
+    Middle("middle")
+}
+
+// https://api.highcharts.com/highcharts/xAxis.title
+// https://api.highcharts.com/highcharts/yAxis.title
+class AAAxisTitle {
+    var align: String? = null
+    var margin: String? = null
+    var offset: Number? = null
+    var rotation: Number? = null
+    var style: AAStyle? = null
+    var text: String? = null
+    var textAlign: String? = null
+    var useHTML: Boolean? = null // 是否使用 HTML 渲染标题
+    var x: Number? = null // 标题相对于水平对齐的偏移量，取值范围为：图表左边距到图表右边距，可以是负值，单位px。 默认是：0.
+    var y: Number? = null // 标题相对于垂直对齐的偏移量，取值范围：图表的上边距（chart.spacingTop ）到图表的下边距（chart.spacingBottom），可以是负值，单位是px。默认值和字体大小有关。
+
+    fun align(prop: AAChartAxisTitleAlignValueType?): AAAxisTitle {
+        align = prop?.value
+        return this
+    }
+
+    fun margin(prop: String?): AAAxisTitle {
+        margin = prop
+        return this
+    }
+
+    fun offset(prop: Number?): AAAxisTitle {
+        offset = prop
+        return this
+    }
+
+    fun rotation(prop: Number?): AAAxisTitle {
+        rotation = prop
+        return this
+    }
+
+    fun style(prop: AAStyle?): AAAxisTitle {
+        style = prop
+        return this
+    }
+
+    fun text(prop: String?): AAAxisTitle {
+        text = prop
+        return this
+    }
+
+    fun textAlign(prop: AAChartAlignType?): AAAxisTitle {
+        textAlign = prop?.value
+        return this
+    }
+
+    fun useHTML(prop: Boolean?): AAAxisTitle {
+        useHTML = prop
+        return this
+    }
+
+    fun x(prop: Number?): AAAxisTitle {
+        x = prop
+        return this
+    }
+
+    fun y(prop: Number?): AAAxisTitle {
+        y = prop
+        return this
+    }
+}