fix(server-storage): Stalker keys by category, keepalive ordering, cut-off probe

- Moving Stalker favorites and history keys items by id and category, so
  a channel and a movie with one id both survive.
- Writes after a page-hide flush wait for its keepalive requests.
- A probe whose body is cut off counts as unreachable and keeps the
  remembered server.
- Settings → Server renders without @defer so settings search can reveal
  its rows on the first visit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/app/server-storage/server-instance-probe.spec.ts

@@ -78,6 +78,14 @@ describe('probeServerInstance', () => {
         for (const fetchFn of [
             jest.fn().mockRejectedValue(new TypeError('Failed to fetch')),
             answer('Bad Gateway', 502),
+            // Headers arrived, then the body was cut off.
+            jest.fn().mockResolvedValue({
+                ok: true,
+                status: 200,
+                json: async () => {
+                    throw new DOMException('aborted', 'AbortError');
+                },
+            }),
         ]) {
             await expect(
                 probeServerInstance({ ...config, fetchFn: fetchFn as never })

apps/web/src/app/server-storage/server-instance-probe.ts

@@ -64,8 +64,11 @@ export async function probeServerInstance(
         return isServerInstance(body) && body.storage === 'server'
             ? { kind: 'server', instance: body }
             : { kind: 'none' };
-    } catch {
-        return { kind: 'none' };
+    } catch (error) {
+        // Unparseable JSON is an answer; a cut-off body is an outage.
+        return error instanceof SyntaxError
+            ? { kind: 'none' }
+            : { kind: 'unreachable' };
     }
 }
 

apps/web/src/app/settings/settings-server-section.component.ts

@@ -22,8 +22,8 @@ import type { ServerStorageStatusResponse } from '@iptvnator/shared/interfaces';
 
 /**
  * Settings → Server: shown only when the PWA runs against self-hosted
- * server storage. Loaded with `@defer`, so other builds never fetch the
- * server-storage code for the settings page.
+ * server storage. Rendered without `@defer` so settings search can reveal
+ * its rows on the first visit; the code rides in the lazy settings chunk.
  */
 @Component({
     selector: 'app-settings-server-section',

apps/web/src/app/settings/settings.component.html

@@ -120,13 +120,9 @@
                         />
                     }
                     @case ('server') {
-                        <!-- Deferred: keeps the server-storage code out of
-                             the settings chunk in every other build. -->
-                        @defer {
-                            <app-settings-server-section
-                                (exportData)="exportData()"
-                            />
-                        }
+                        <app-settings-server-section
+                            (exportData)="exportData()"
+                        />
                     }
                     @case ('backup') {
                         <!-- Backup & data: the former Reset page is this