feat(player): the YouTube player and the file viewer are named in the address

The player names what it plays in its own history entry (watch, wrel, wtab): a reload or a
bookmark reopens it on the page that hosts it, with that page's list as the queue, or alone
from the catalog (GET /api/videos/{id}/row); a page that hosts none gets the shell's. Back
lands on the page's address without it (useBackToClose's url; ui/Modal passes it on). The
Files viewer and player do the same (fview, fplay). The Plex and channel-manager views are
always written in full, as their fallback is remembered state.

frontend/src/modules/feed/Feed.playerSession.dom.test.tsx

@@ -53,11 +53,13 @@ vi.mock("../../features/player/PlayerModal", async () => {
   return {
     default: function Player({
       video,
+      queue,
       onState,
       onWrite,
       onClose,
     }: {
       video: { id: string };
+      queue?: { id: string }[];
       onState: (id: string, status: string, v?: unknown) => void;
       onWrite?: (write: Promise<unknown>) => void;
       onClose: () => void;
@@ -71,6 +73,9 @@ vi.mock("../../features/player/PlayerModal", async () => {
       );
       return (
         <div>
+          <p>
+            playing {video.id} in {queue ? queue.map((v) => v.id).join(",") : "no list"}
+          </p>
           <button onClick={() => onState(video.id, "watched")}>mark</button>
           <button
             onClick={() =>
@@ -116,6 +121,7 @@ afterEach(() => {
   player.watchOnUnmount = false;
   player.flush = null;
   clearAll();
+  window.history.replaceState(null, "", "/");
 });
 
 // A cached related list (the player's, kept for the session) holding these videos.
@@ -190,6 +196,23 @@ function mount({
   return { qc, feed, summary };
 }
 
+// The URL is the view: a reload or a bookmark of the player reopens it once the list is in.
+describe("Feed — a player the address names", () => {
+  it("reopens on its video, the list as its queue", async () => {
+    window.history.replaceState(null, "", "/?watch=v1");
+    mount();
+    expect(await screen.findByText("playing v1 in v1")).toBeTruthy();
+  });
+
+  it("plays a video the loaded list does not hold alone, from the catalog", async () => {
+    window.history.replaceState(null, "", "/?watch=far");
+    const row = vi.spyOn(api, "videoRow").mockResolvedValue({ ...video("new"), id: "far" });
+    mount();
+    expect(await screen.findByText("playing far in no list")).toBeTruthy();
+    expect(row).toHaveBeenCalledWith("far");
+  });
+});
+
 describe("Feed — a video marked watched in the player", () => {
   it("stays out of an Unwatched view when the player writes its position into the cache", async () => {
     const { qc } = mount();