refactor(ai): extract updateTorrentStatus from js/app.js (agent)

Moved torrent status update logic to `js/ui/torrentStatusController.js` to improve separation of concerns as per `AGENTS.md`. The controller accepts a `getVideoModal` accessor and an `onRemovePoster` callback to decouple it from direct `videoModal` or `Application` dependencies. Added unit tests in `tests/ui/torrentStatusController.test.mjs`.

tests/ui/torrentStatusController.test.mjs

@@ -0,0 +1,66 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import TorrentStatusController from "../../js/ui/torrentStatusController.js";
+
+test("TorrentStatusController throws if accessor is missing", (t) => {
+  assert.throws(() => new TorrentStatusController({}), /accessor/);
+});
+
+test("TorrentStatusController updates video modal and calls onRemovePoster", (t) => {
+  let modalState = {};
+  let posterRemoved = false;
+
+  const mockModal = {
+    updateStatus: (msg) => { modalState.status = msg; },
+    updateProgress: (msg) => { modalState.progress = msg; },
+    updatePeers: (msg) => { modalState.peers = msg; },
+    updateSpeed: (msg) => { modalState.speed = msg; },
+    updateDownloaded: (msg) => { modalState.downloaded = msg; },
+  };
+
+  const onRemovePoster = (reason) => {
+    posterRemoved = reason;
+  };
+
+  const controller = new TorrentStatusController({
+    getVideoModal: () => mockModal,
+    onRemovePoster
+  });
+
+  // Test basic update
+  controller.update({
+    ready: false,
+    progress: 0.5,
+    numPeers: 5,
+    downloadSpeed: 1024 * 100, // 100 KB/s
+    downloaded: 1024 * 1024 * 10, // 10 MB
+    length: 1024 * 1024 * 100 // 100 MB
+  });
+
+  assert.equal(modalState.status, "Downloading");
+  assert.equal(modalState.progress, "50.00%");
+  assert.equal(modalState.peers, "Peers: 5");
+  assert.equal(modalState.speed, "100.00 KB/s");
+  assert.equal(modalState.downloaded, "10.00 MB / 100.00 MB");
+  assert.equal(posterRemoved, "torrent-progress");
+
+  // Test complete
+  controller.update({
+    ready: true,
+    progress: 1,
+    numPeers: 0,
+    downloadSpeed: 0,
+    downloaded: 1024 * 1024 * 100,
+    length: 1024 * 1024 * 100
+  });
+
+  // It sets "Complete" then "Ready to play" if ready is true
+  assert.equal(modalState.status, "Ready to play");
+  assert.equal(modalState.progress, "100.00%");
+  assert.equal(posterRemoved, "torrent-ready-flag");
+});
+
+test("TorrentStatusController handles missing modal gracefully", (t) => {
+  const controller = new TorrentStatusController({ getVideoModal: () => null });
+  assert.doesNotThrow(() => controller.update({ progress: 0.5 }));
+});