feat(desktop): upload progress on the taskbar button (cinny-desktop #10)

Upload atoms now also report into an app-wide `uploadProgressAtom`, and
`aggregateUploadProgress` turns every in-flight upload into one taskbar
state: byte-weighted percentage while uploading, indeterminate until a
size is known, red after a failure (held 4 s, then cleared), none when
done. Cancelled uploads just disappear. `useTauriTaskbarProgress` sends it
to the native `set_taskbar_progress`, at most ~4 times a second, always
ending on the latest state.

Verified with a throttled 6 MB upload: 0% → 99% at 250 ms steps, then
cleared; with the upload request aborted: 0% → error → cleared after 4 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/state/upload.ts

@@ -4,6 +4,7 @@ import { MatrixClient, UploadResponse, UploadProgress, MatrixError } from 'matri
 import { useCallback, useRef } from 'react';
 import { useThrottle } from '../hooks/useThrottle';
 import { uploadContent, TUploadContent } from '../utils/matrix';
+import { uploadProgressAtom } from './uploadProgress';
 
 export enum UploadStatus {
   Idle = 'idle',
@@ -61,7 +62,17 @@ export const createUploadAtom = (file: TUploadContent) => {
     (get) => get(baseUploadAtom),
     (get, set, update) => {
       const uploadState = get(baseUploadAtom);
+      // [cinny-desktop #10] Mirror into the app-wide progress map for the
+      // desktop taskbar bar. Cancelled uploads just disappear (no red bar).
+      const track = (entry: { loaded: number; total: number; failed: boolean } | undefined) =>
+        set(uploadProgressAtom, (prev) => {
+          const next = new Map(prev);
+          if (entry) next.set(file, { ...entry, updatedAt: Date.now() });
+          else next.delete(file);
+          return next;
+        });
       if ('promise' in update) {
+        track({ loaded: 0, total: file.size, failed: false });
         set(baseUploadAtom, {
           status: UploadStatus.Loading,
           file,
@@ -71,6 +82,11 @@ export const createUploadAtom = (file: TUploadContent) => {
         return;
       }
       if ('progress' in update && uploadState.status === UploadStatus.Loading) {
+        track({
+          loaded: update.progress.loaded,
+          total: update.progress.total || file.size,
+          failed: false,
+        });
         set(baseUploadAtom, {
           ...uploadState,
           progress: update.progress,
@@ -78,6 +94,7 @@ export const createUploadAtom = (file: TUploadContent) => {
         return;
       }
       if ('mxc' in update) {
+        track(undefined);
         set(baseUploadAtom, {
           status: UploadStatus.Success,
           file,
@@ -86,6 +103,11 @@ export const createUploadAtom = (file: TUploadContent) => {
         return;
       }
       if ('error' in update) {
+        const cancelled =
+          update.error?.name === 'AbortError' || /abort/i.test(update.error?.message ?? '');
+        const loaded =
+          uploadState.status === UploadStatus.Loading ? uploadState.progress.loaded : 0;
+        track(cancelled ? undefined : { loaded, total: file.size, failed: true });
         set(baseUploadAtom, {
           status: UploadStatus.Error,
           file,