feat(app): scrollback search bar (⌘F) on the focused panel

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/src/CenterToolbar.tsx

@@ -3,13 +3,14 @@ import { COLORS, FONT } from "./theme";
 import { PresetPicker } from "./PresetPicker";
 
 /** Top-of-grid toolbar: layout presets on the left, scrollback search on the right (search is a mock). */
-export function CenterToolbar({ selected, onSelect }: { selected: string; onSelect: (id: string) => void }) {
+export function CenterToolbar({ selected, onSelect, onOpenSearch }: { selected: string; onSelect: (id: string) => void; onOpenSearch: () => void }) {
   return (
     <div style={{ display: "flex", alignItems: "center", gap: 8, padding: "0 12px", height: 46, borderBottom: `1px solid ${COLORS.borderSubtle}` }}>
       <PresetPicker selected={selected} onSelect={onSelect} />
       <div style={{ flex: 1 }} />
       <div
-        title="Search scrollback (mock)"
+        title="Search scrollback"
+        onClick={onOpenSearch}
         style={{
           display: "flex", alignItems: "center", gap: 6, height: 24, padding: "0 8px", borderRadius: 6,
           background: COLORS.bgPanel, border: `1px solid ${COLORS.borderSubtle}`, cursor: "pointer",