feat: Library bulk download + list virtualization for large channels

Add a source-wide "Select all" across all playlist groups, and make one
click queue every indexed video (the previous 100-per-click cap is gone).
Bulk download skips items that are already downloaded or in flight, so it
can't enqueue duplicates, and it includes failed/canceled ones so it also
retries them.

Make the UI hold up at channel scale (1000s of videos): virtualize both
the Downloads queue and the Library item list with @tanstack/react-virtual
so only on-screen rows hit the DOM, memoize the queue row so they don't all
reconcile on every progress tick, and batch the enqueue so queuing a whole
channel stays O(n) instead of O(n^2).

- VirtualList: reusable windowed list that owns its own scroll container
- DownloadsView: virtualized, flex-filled queue
- LibraryView: groups flattened to rows; virtualized panel above 100 rows,
  inline below so small sources are unchanged
- QueueItem: React.memo
- downloads store: addMany (one state update + one pump); sources:
  enqueue the whole selection via addMany, no cap

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package-lock.json

@@ -1,16 +1,17 @@
 {
   "name": "aerofetch",
-  "version": "0.1.0",
+  "version": "0.4.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "aerofetch",
-      "version": "0.1.0",
+      "version": "0.4.1",
       "dependencies": {
         "@electron-toolkit/utils": "^4.0.0",
         "@fluentui/react-components": "^9.74.1",
         "@fluentui/react-icons": "^2.0.330",
+        "@tanstack/react-virtual": "^3.14.3",
         "electron-store": "^11.0.2",
         "react": "^19.2.7",
         "react-dom": "^19.2.7",
@@ -3373,6 +3374,33 @@
         "node": ">=10"
       }
     },
+    "node_modules/@tanstack/react-virtual": {
+      "version": "3.14.3",
+      "resolved": "https://registry.npmjs.org/@tanstack/react-virtual/-/react-virtual-3.14.3.tgz",
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+      "license": "MIT",
+      "dependencies": {
+        "@tanstack/virtual-core": "3.17.1"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      },
+      "peerDependencies": {
+        "react": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0",
+        "react-dom": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0"
+      }
+    },
+    "node_modules/@tanstack/virtual-core": {
+      "version": "3.17.1",
+      "resolved": "https://registry.npmjs.org/@tanstack/virtual-core/-/virtual-core-3.17.1.tgz",
+      "integrity": "sha512-VZyW2Uiml5tmBZwPGrSD3Sz73OxzljQMCmzYHsUTPEuTsERf5xwa+uWb01xEzkz3ZSYTjj8NEb/mKHvgKxyZdA==",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      }
+    },
     "node_modules/@types/babel__core": {
       "version": "7.20.5",
       "resolved": "https://registry.npmjs.org/@types/babel__core/-/babel__core-7.20.5.tgz",