M7: add data tables beneath charts

Add command and UI controls for chart data tables, shared chart and PDF rendering, and native XLSX persistence. Cover live values, blanks, formatting, alignment, undo/redo, bounds and table flags with regression tests.

Co-Authored-By: Codex <noreply@openai.com>

crates/model/src/features.rs

@@ -540,6 +540,22 @@ impl Trendline {
     }
 }
 
+/// A chart's data table (`c:dTable`), independent of the chart legend.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(default)]
+pub struct ChartDataTable {
+    pub show_keys: bool,
+    pub horizontal_border: bool,
+    pub vertical_border: bool,
+    pub outline: bool,
+}
+
+impl Default for ChartDataTable {
+    fn default() -> Self {
+        Self { show_keys: true, horizontal_border: true, vertical_border: true, outline: true }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub struct Chart {
     pub id: u32,
@@ -549,6 +565,8 @@ pub struct Chart {
     pub series: Vec<Series>,
     pub legend: LegendPos,
     pub data_labels: bool,
+    #[serde(default)]
+    pub data_table: Option<ChartDataTable>,
     pub gridlines: bool,
     pub style: u32,
     pub x_title: Option<String>,
@@ -562,6 +580,30 @@ pub struct Chart {
     pub pivot: Option<String>,
 }
 
+impl Chart {
+    /// Data tables belong to category-axis column, bar, line and area charts.
+    pub fn supports_data_table(&self) -> bool {
+        let eligible = |kind| {
+            matches!(
+                kind,
+                ChartKind::ColumnClustered
+                    | ChartKind::ColumnStacked
+                    | ChartKind::ColumnStacked100
+                    | ChartKind::BarClustered
+                    | ChartKind::BarStacked
+                    | ChartKind::BarStacked100
+                    | ChartKind::Line
+                    | ChartKind::LineMarkers
+                    | ChartKind::LineStacked
+                    | ChartKind::Area
+                    | ChartKind::AreaStacked
+                    | ChartKind::AreaStacked100
+            )
+        };
+        eligible(self.kind) || (self.kind == ChartKind::Combo && self.series.iter().all(|s| eligible(s.kind.unwrap_or(ChartKind::Line))))
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub struct Image {
     pub id: u32,