Use buffer font in the terminal inline assistant (#18009)

This PR is a follow up to
https://github.com/zed-industries/zed/pull/17875.

Release Notes:

- N/A

crates/assistant/src/terminal_inline_assistant.rs

@@ -570,7 +570,7 @@ impl Render for PromptEditor {
             .bg(cx.theme().colors().editor_background)
             .border_y_1()
             .border_color(cx.theme().status().info_border)
-            .py_1p5()
+            .py_2()
             .h_full()
             .w_full()
             .on_action(cx.listener(Self::confirm))
@@ -949,12 +949,11 @@ impl PromptEditor {
             } else {
                 cx.theme().colors().text
             },
-            font_family: settings.ui_font.family.clone(),
-            font_features: settings.ui_font.features.clone(),
-            font_fallbacks: settings.ui_font.fallbacks.clone(),
-            font_size: rems(0.875).into(),
-            font_weight: settings.ui_font.weight,
-            line_height: relative(1.3),
+            font_family: settings.buffer_font.family.clone(),
+            font_fallbacks: settings.buffer_font.fallbacks.clone(),
+            font_size: settings.buffer_font_size.into(),
+            font_weight: settings.buffer_font.weight,
+            line_height: relative(settings.buffer_line_height.value()),
             ..Default::default()
         };
         EditorElement::new(