T24f Agent: control and cost

HumanInputRequest asks a question with answers to pick and a line to
write one; CostBreakdown totals a session and splits it by part.
InterruptButton, TokenUsageChart, TraceViewer and EvalResultTable
point to chat::stop_button, a stacked BarChart, TimelineProfiler and
DataTable.

UsageBar shows amounts as its owner writes them. MemoryPanel and
HumanInputRequest share agent::line::send_line; the chapter's bool
callbacks take forms::OnFlag.

DataTable scrolls columns wider than its box sideways, pinned or not,
and leaves a plain wheel to the page; sortable headers are Tab stops.
TimelineProfiler fits its ruler to its lane, its spans are Tab stops,
and a picked span takes accent.

src/agent/permission.rs

@@ -8,13 +8,12 @@ use gpui::{
 use crate::{
     buttons::{Button, ButtonVariant},
     chat::CodeBlock,
+    forms::OnFlag,
     overlays::Dialog,
     primitives::{Icon, IconName},
     theme::{ActiveTheme, IconSize, Radius, TextSize},
 };
 
-type OnAnswer = Rc<dyn Fn(bool, &mut Window, &mut App)>;
-
 /// Asks before a tool runs: what it will do and its arguments, then Deny or Run. Escape, the scrim and Deny refuse it. Render it while the call waits.
 #[derive(IntoElement)]
 pub struct ToolApprovalDialog {
@@ -22,7 +21,7 @@ pub struct ToolApprovalDialog {
     tool: SharedString,
     arguments: SharedString,
     detail: Option<SharedString>,
-    on_answer: OnAnswer,
+    on_answer: OnFlag,
 }
 
 impl ToolApprovalDialog {