feat(updater): show in-app progress during app update

Replace native update dialogs with an in-app modal that shows a live
download progress bar and installing state, so updates no longer feel
abrupt. Drives the plugin's downloadAndInstall progress events through a
zustand store.

src/updater.ts

@@ -1,31 +1,58 @@
 import { check } from "@tauri-apps/plugin-updater";
 import { relaunch } from "@tauri-apps/plugin-process";
-import { ask, message } from "@tauri-apps/plugin-dialog";
+import { useUpdater } from "./store/useUpdater";
 
-let running = false;
+let checking = false;
 
 export async function checkForUpdates(silent: boolean) {
-  if (running) return;
-  running = true;
+  if (checking) return;
+  checking = true;
+  const store = useUpdater.getState();
+  if (!silent) store.set({ phase: "checking", error: "" });
   try {
     const update = await check();
     if (!update) {
-      if (!silent) await message("margin is up to date.", { title: "Check for Updates" });
+      store.set(silent ? { phase: "idle" } : { phase: "uptodate" });
       return;
     }
-    const notes = update.body ? `\n\n${update.body}` : "";
-    const install = await ask(`margin ${update.version} is available.${notes}\n\nInstall now and restart?`, {
-      title: "Update Available",
-      kind: "info",
+    store.set({
+      phase: "available",
+      update,
+      version: update.version,
+      notes: update.body ?? "",
+      downloaded: 0,
+      total: 0,
+      error: "",
     });
-    if (!install) return;
-    await update.downloadAndInstall();
-    await relaunch();
   } catch (err) {
-    if (!silent) {
-      await message(`Could not check for updates.\n\n${err}`, { title: "Update Failed", kind: "error" });
-    }
+    store.set(silent ? { phase: "idle" } : { phase: "error", error: String(err) });
   } finally {
-    running = false;
+    checking = false;
   }
 }
+
+export async function installUpdate() {
+  const { update, phase } = useUpdater.getState();
+  if (!update || phase === "downloading" || phase === "installing") return;
+  try {
+    useUpdater.getState().set({ phase: "downloading", downloaded: 0, total: 0 });
+    await update.downloadAndInstall((event) => {
+      const s = useUpdater.getState();
+      if (event.event === "Started") {
+        s.set({ total: event.data.contentLength ?? 0, downloaded: 0 });
+      } else if (event.event === "Progress") {
+        s.set({ downloaded: s.downloaded + event.data.chunkLength });
+      } else if (event.event === "Finished") {
+        s.set({ phase: "installing" });
+      }
+    });
+    useUpdater.getState().set({ phase: "installing" });
+    await relaunch();
+  } catch (err) {
+    useUpdater.getState().set({ phase: "error", error: String(err) });
+  }
+}
+
+export function dismissUpdate() {
+  useUpdater.getState().reset();
+}