agent: Add max mode on text threads (#31361)

Related discussions #30240 #30596

Release Notes:

- Added the ability to use max mode on text threads.

---------

Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

crates/assistant_context_editor/src/max_mode_tooltip.rs

@@ -0,0 +1,60 @@
+use gpui::{Context, 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 = if self.selected {
+            IconName::ZedBurnModeOn
+        } else {
+            IconName::ZedBurnMode
+        };
+
+        let title = h_flex()
+            .gap_1()
+            .child(Icon::new(icon).size(IconSize::Small))
+            .child(Label::new("Burn Mode"));
+
+        tooltip_container(window, cx, |this, _, _| {
+            this.gap_0p5()
+                .map(|header| if self.selected {
+                    header.child(
+                        h_flex()
+                            .justify_between()
+                            .child(title)
+                            .child(
+                                h_flex()
+                                    .gap_0p5()
+                                    .child(Icon::new(IconName::Check).size(IconSize::XSmall).color(Color::Accent))
+                                    .child(Label::new("Turned On").size(LabelSize::XSmall).color(Color::Accent))
+                            )
+                    )
+                } else {
+                    header.child(title)
+                })
+                .child(
+                    div()
+                        .max_w_72()
+                        .child(
+                            Label::new("Enables models to use large context windows, unlimited tool calls, and other capabilities for expanded reasoning, offering an unfettered agentic experience.")
+                                .size(LabelSize::Small)
+                                .color(Color::Muted)
+                        )
+                )
+        })
+    }
+}