feat: allow active update downloads to be canceled

Keep the dialog cancel action available during update downloads, abort the active network stream, and surface a clean canceled state with retry support. Normalize cancellation across updater, main process, renderer, and translations with regression coverage.

tests/i18n.test.js

@@ -116,6 +116,11 @@ test('rare account, backup, update, and confirmation states translate in both di
     ['Ein Update wird bereits vorbereitet', 'An update is already being prepared'],
     ['Die Anwendung ist noch nicht bereit, das Update sicher zu installieren', 'The application is not yet ready to install the update safely'],
     ['Update abgebrochen', 'Update canceled'],
+    ['Download abbrechen', 'Cancel download'],
+    ['Abbrechen…', 'Cancelling…'],
+    ['Download abgebrochen', 'Download canceled'],
+    ['Wiederholen', 'Retry'],
+    ['Update konnte nicht abgebrochen werden', 'The update could not be canceled'],
     ['Ausgewählte Einträge entfernen?', 'Remove selected entries?'],
     ['Export fehlgeschlagen', 'Export failed'],
     ['Backup exportiert', 'Backup exported'],

tests/ui-smoke.js

@@ -2469,6 +2469,7 @@ setTimeout(async () => {
         hidden: overlay.getAttribute('aria-hidden'),
         closeDisabled: document.getElementById('updateCloseBtn').disabled,
         dismissDisabled: document.getElementById('dismissUpdateBtn').disabled,
+        dismissText: document.getElementById('dismissUpdateBtn').textContent,
         headerHidden: header.hidden,
         messageHidden: document.getElementById('updateMessage').hidden,
         messageText: document.getElementById('updateMessage').textContent,
@@ -2476,7 +2477,7 @@ setTimeout(async () => {
         progressText: progress.getAttribute('aria-valuetext')
       };
     })()\`);
-    check('Busy update keeps its progress dialog open', busyUpdateState.display === 'flex' && busyUpdateState.hidden === 'false' && busyUpdateState.closeDisabled === true && busyUpdateState.dismissDisabled === true && busyUpdateState.headerHidden === false);
+    check('Busy update keeps its progress dialog open with download cancellation available', busyUpdateState.display === 'flex' && busyUpdateState.hidden === 'false' && busyUpdateState.closeDisabled === true && busyUpdateState.dismissDisabled === false && busyUpdateState.dismissText === 'Download abbrechen' && busyUpdateState.headerHidden === false);
     check('Update progress exposes an accessible live value', busyUpdateState.progressLabel === 'Update-Fortschritt' && busyUpdateState.progressText === 'Download 50%');
     check('Busy update shows progress only below the bar', busyUpdateState.messageHidden === true && busyUpdateState.messageText === 'Update v9.9.9 verfügbar');
 

tests/updater-version.test.js

@@ -7,7 +7,7 @@ const crypto = require('node:crypto');
 const Module = require('node:module');
 const { pathToFileURL } = require('node:url');
 
-const { isNewer, resolveReleaseVersion, fetchGithubReleaseNotes, prepareUpdate, launchPreparedUpdate, pickSetupAsset, parseLatestYml, createUpdateAnnouncementState } = require('../lib/updater');
+const { isNewer, resolveReleaseVersion, fetchGithubReleaseNotes, prepareUpdate, launchPreparedUpdate, pickSetupAsset, parseLatestYml, createUpdateAnnouncementState, abortUpdate } = require('../lib/updater');
 const releasePlanUrl = pathToFileURL(path.resolve(__dirname, '../scripts/release-plan.mjs')).href;
 
 test('bridge title resolves product version instead of transport tag', () => {
@@ -152,6 +152,61 @@ test('buffered installer downloads yield between progress updates so the rendere
   }
 });
 
+test('cancelling an active installer download reports an aborted state', async () => {
+  const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'mhu-updater-abort-test-'));
+  const installer = Buffer.alloc(128 * 1024, 0);
+  installer[0] = 0x4d;
+  installer[1] = 0x5a;
+  const progress = [];
+  let reads = 0;
+
+  try {
+    await assert.rejects(
+      prepareUpdate(value => {
+        progress.push(value);
+        if (value.stage === 'downloading') abortUpdate();
+      }, {
+        checkResult: {
+          available: true,
+          assetUrl: 'https://update.invalid/setup.exe',
+          assetName: 'setup.exe',
+          assetSize: installer.length,
+          remoteVersion: '2.2.0',
+          latestYmlUrl: 'https://update.invalid/latest.yml'
+        },
+        tempDir,
+        fetchImpl: async url => url.endsWith('latest.yml')
+          ? {
+              ok: true,
+              status: 200,
+              text: async () => `version: 2.2.0\npath: setup.exe\nsha512: ${crypto.createHash('sha512').update(installer).digest('base64')}\nsize: ${installer.length}\n`
+            }
+          : {
+              ok: true,
+              status: 200,
+              body: {
+                getReader: () => ({
+                  read: async () => {
+                    reads++;
+                    return reads === 1
+                      ? { done: false, value: installer.subarray(0, installer.length / 2) }
+                      : { done: false, value: installer.subarray(installer.length / 2) };
+                  }
+                })
+              }
+            }
+      }),
+      /Update abgebrochen/
+    );
+
+    assert.equal(progress.at(-1).stage, 'aborted');
+    assert.equal(progress.at(-1).error, 'Update abgebrochen');
+    assert.equal(fs.existsSync(path.join(tempDir, 'setup.exe')), false);
+  } finally {
+    fs.rmSync(tempDir, { recursive: true, force: true });
+  }
+});
+
 test('update preparation refreshes a cached release before downloading the installer', async () => {
   const updaterPath = require.resolve('../lib/updater');
   const originalLoad = Module._load;