feat: add PreCompact hook support (#267)

Parses [PreCompact Hook] events from the CLI stream and emits a claude:pre-compact Tauri event. Shows a "Compacting context..." toast and thinking state on the frontend, complementing the existing PostCompact handling.

src/lib/tauri.ts

@@ -11,6 +11,7 @@ import type {
   ElicitationEvent,
   PermissionPromptEvent,
   PostCompactEvent,
+  PreCompactEvent,
   StopFailureEvent,
   UserQuestionEvent,
 } from "$lib/types/messages";
@@ -661,6 +662,12 @@ export async function initializeTauriListeners() {
   });
   unlisteners.push(stopFailureUnlisten);
 
+  const preCompactUnlisten = await listen<PreCompactEvent>("claude:pre-compact", () => {
+    toastStore.addInfo("Compacting context...", "🗜️");
+    characterState.setTemporaryState("thinking", 3000);
+  });
+  unlisteners.push(preCompactUnlisten);
+
   const postCompactUnlisten = await listen<PostCompactEvent>("claude:post-compact", () => {
     toastStore.addInfo("Context compacted", "🗜️");
     characterState.setTemporaryState("success", 2000);