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/lib/queryKeys.test.ts

@@ -33,6 +33,7 @@ describe("qk — single-id and scalar keys", () => {
   it("returns [root, id]", () => {
     expect(qk.channel("c1")).toEqual(["channel", "c1"]);
     expect(qk.videoDetail("v1")).toEqual(["video-detail", "v1"]);
+    expect(qk.videoRow("v1")).toEqual(["video-row", "v1"]);
     expect(qk.playlistMembership("v1")).toEqual(["playlist-membership", "v1"]);
     expect(qk.plexItem("i1")).toEqual(["plex-item", "i1"]);
     expect(qk.plexPlaylist(9)).toEqual(["plex-playlist", 9]);