fix(nav): the address follows the view through overlays, reloads and Back (review round 1)

- A URL mirror names the view again on every entry Back or Forward lands on, so a change made
  under a dialog, a drawer or a sub-view is not undone by the next reload.
- A view pushed from the entry a reload under a dialog started from no longer inherits its overlay
  mark; a reload under two overlays closes onto the page in one step.
- The linked player reopens over a live search, gives itself up when its list moves first, and
  plays alone over an emptied playlist; a capped Files list keeps the link it cannot resolve.
- The Feed press over a channel ends the search; leaving a search ends its asked mark; Files and
  Playlists searches end with their page; the feed always names its view and debounces its search.
- Search-box keys are declared per module and kept out of the client log below TRACE.
- Writers outside lib/ go through codecs; the URL contract scans computed keys, overlay writers and
  two-line reads, and holds every page to a bookmark round trip (Config, Activity, Playlists and the
  Files sort and viewer added).

frontend/src/lib/urlState.dom.test.ts

@@ -127,13 +127,13 @@ describe("a page opened at a path that starts with //", () => {
 });
 
 describe("filterParamUpdates", () => {
-  it("maps non-default filters to values and defaults to null (delete)", () => {
+  it("maps non-default filters to values and other defaults to null (delete)", () => {
     const f: FeedFilters = { ...DEFAULTS, q: "react", tags: [3, 7], show: "watched" };
     const upd = filterParamUpdates(f);
     expect(upd.q).toBe("react");
     expect(upd.tags).toBe("3,7");
     expect(upd.show).toBe("watched");
-    expect(upd.sort).toBeNull(); // default "newest" is not emitted → cleared
+    expect(upd.sort).toBe("newest"); // the view and the order are always named, defaults too
     expect(upd.scope).toBeNull();
   });