feat(decky): self-update without the store + Gaming-Mode launch polish, and ship the Steam Deck docs

Plugin self-update (no Decky store): CI publishes a per-channel manifest.json
({version, immutable per-version artifact, sha256}) beside the zip and bakes
update.json {channel, manifest} into the plugin. main.py `check_update` reads the
installed version from package.json (the value Decky reports — not plugin.json),
fetches the channel manifest, and the frontend shows an "Update to vX" button that
drives Decky Loader's own install RPC (root downloads + SHA-256-verifies + hot-reloads).
CI now stamps a plain-numeric semver (0.3.<run> canary / X.Y.Z stable) into
package.json — a -ciN suffix would mis-order under compare-versions.

Linux client: `--fullscreen` (plus SteamDeck/gamescope env fallback) enters GTK
fullscreen on stream start so Gaming-Mode chrome is hidden; native-mode resolution
falls back to the display's first monitor when the window isn't mapped yet (was
dropping to the 1080p floor — wrong on the Deck's 1280×800); add a confirmed
"Remove saved host" action (KnownHosts::remove_by_fp).

Docs: new docs/steam-deck.md (Decky install/pair/stream/self-update/troubleshooting),
wired into meta.json nav, and cross-linked from clients/install-client/channels. This
is the page docs.punktfunk.unom.io/docs/steam-deck — the website's download link
pointed at it before it existed; committing it makes that link resolve.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/decky/src/steam.ts

@@ -24,12 +24,31 @@ declare const SteamClient: {
     SetShortcutExe(appId: number, exe: string): void;
     SetShortcutStartDir(appId: number, dir: string): void;
     SetAppLaunchOptions(appId: number, options: string): void;
-    SetAppHidden(appId: number, hidden: boolean): void;
     RunGame(gameId: string, _unused: string, _i: number, _j: number): void;
     TerminateApp(gameId: string, _b: boolean): void;
   };
 };
 
+// Steam removed `SteamClient.Apps.SetAppHidden`. Hiding a non-Steam shortcut now goes through
+// `collectionStore.SetAppsAsHidden([appId], true)` — but that looks the app up in appStore, which
+// only registers a freshly-created shortcut a moment later (calling it immediately throws on a
+// null overview). So hiding is BEST-EFFORT + DEFERRED and must NEVER block the launch.
+declare const collectionStore:
+  | { SetAppsAsHidden?: (appIds: number[], hidden: boolean) => void }
+  | undefined;
+
+function hideShortcut(appId: number): void {
+  const attempt = () => {
+    try {
+      collectionStore?.SetAppsAsHidden?.([appId], true);
+    } catch {
+      /* overview not registered yet, or the API changed — cosmetic, ignore */
+    }
+  };
+  attempt(); // succeeds immediately for an already-registered (reused) shortcut
+  setTimeout(attempt, 2500); // fresh shortcut: retry once its app overview lands
+}
+
 const SHORTCUT_NAME = "punktfunk";
 
 // The 64-bit "gameid" RunGame wants, derived from a 32-bit non-Steam shortcut appId: the
@@ -88,7 +107,8 @@ async function ensureShortcut(): Promise<number> {
   );
   SteamClient.Apps.SetShortcutName(appId, SHORTCUT_NAME);
   // Hide it from the library — it's an implementation detail, launched programmatically.
-  SteamClient.Apps.SetAppHidden(appId, true);
+  // Best-effort + deferred (see hideShortcut); never let it block the launch.
+  hideShortcut(appId);
   rememberAppId(appId);
   return appId;
 }