fix(ui): prevent grid column overflow with proper truncation

Fix column header and cell text truncation to prevent overflow
when text width equals column width. Changed truncate() calls to
use cw.saturating_sub(1) instead of cw, ensuring at least one
character of padding remains.

Affected areas:
- Column header labels (left-aligned)
- Column header labels (right-aligned)
- Cell values
- Total/summary rows

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/Qwen3.5-35B-A3B-GGUF:Q5_K_M)

src/ui/grid.rs

@@ -218,7 +218,7 @@ impl<'a> GridWidget<'a> {
                 buf.set_string(
                     x,
                     y,
-                    format!("{:<width$}", truncate(&label, cw), width = cw),
+                    format!("{:<width$}", truncate(&label, cw.saturating_sub(1)), width = cw),
                     group_style,
                 );
             }
@@ -260,7 +260,7 @@ impl<'a> GridWidget<'a> {
                 buf.set_string(
                     x,
                     y,
-                    format!("{:>width$}", truncate(&label, cw), width = cw),
+                    format!("{:>width$}", truncate(&label, cw.saturating_sub(1)), width = cw),
                     styled,
                 );
             }
@@ -434,7 +434,11 @@ impl<'a> GridWidget<'a> {
                         buf.set_string(
                             x,
                             y,
-                            format!("{:>width$}", truncate(&cell_str, cw), width = cw),
+                            format!(
+                                "{:>width$}",
+                                truncate(&cell_str, cw.saturating_sub(1)),
+                                width = cw
+                            ),
                             cell_style,
                         );
                     }
@@ -495,7 +499,11 @@ impl<'a> GridWidget<'a> {
                     buf.set_string(
                         x,
                         y,
-                        format!("{:>width$}", truncate(&total_str, cw), width = cw),
+                        format!(
+                            "{:>width$}",
+                            truncate(&total_str, cw.saturating_sub(1)),
+                            width = cw
+                        ),
                         Style::default()
                             .fg(Color::Yellow)
                             .add_modifier(Modifier::BOLD),