Cleanup remaining references to max mode (#33509)

Release Notes:

- N/A

crates/agent_ui/src/burn_mode_tooltip.rs

@@ -0,0 +1,61 @@
+use gpui::{Context, FontWeight, IntoElement, Render, Window};
+use ui::{prelude::*, tooltip_container};
+
+pub struct MaxModeTooltip {
+    selected: bool,
+}
+
+impl MaxModeTooltip {
+    pub fn new() -> Self {
+        Self { selected: false }
+    }
+
+    pub fn selected(mut self, selected: bool) -> Self {
+        self.selected = selected;
+        self
+    }
+}
+
+impl Render for MaxModeTooltip {
+    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let (icon, color) = if self.selected {
+            (IconName::ZedBurnModeOn, Color::Error)
+        } else {
+            (IconName::ZedBurnMode, Color::Default)
+        };
+
+        let turned_on = h_flex()
+            .h_4()
+            .px_1()
+            .border_1()
+            .border_color(cx.theme().colors().border)
+            .bg(cx.theme().colors().text_accent.opacity(0.1))
+            .rounded_sm()
+            .child(
+                Label::new("ON")
+                    .size(LabelSize::XSmall)
+                    .weight(FontWeight::SEMIBOLD)
+                    .color(Color::Accent),
+            );
+
+        let title = h_flex()
+            .gap_1p5()
+            .child(Icon::new(icon).size(IconSize::Small).color(color))
+            .child(Label::new("Burn Mode"))
+            .when(self.selected, |title| title.child(turned_on));
+
+        tooltip_container(window, cx, |this, _, _| {
+            this
+                .child(title)
+                .child(
+                    div()
+                        .max_w_64()
+                        .child(
+                            Label::new("Enables models to use large context windows, unlimited tool calls, and other capabilities for expanded reasoning.")
+                                .size(LabelSize::Small)
+                                .color(Color::Muted)
+                        )
+                )
+        })
+    }
+}