docs(bazzite): warn on the user-facing page that 0.26.0-1 cannot stream the Desktop

packaging/bazzite/README.md already carries this, but that file ships inside the repo — the page a
field user actually lands on is /docs/bazzite, and it said only that the virtual output 'needs no
config'. On 0.26.0-1 that reads as a lie: the image granted the host CAP_SYS_NICE, so KWin cannot
read the /proc/<pid>/exe it identifies clients by, the shipped .desktop can never match, and every
Desktop session dies with 'KWin does not expose zkde_screencast_unstable_v1 to this client' —
looking exactly like the setup on that page was done wrong.

Says so, and gives the only repair that works: a merged sysext's /usr is read-only, so it is the
next image (punktfunk-sysext update), not a setcap -r. Notes Gaming Mode is unaffected.

Written as a bolded blockquote, the admonition style every other page uses. NOT a {{< callout >}}
shortcode — this site is Fumadocs/MDX, not Hugo, and no shortcode exists anywhere in it. Verified by
running the real build (bun install + vite build) rather than assuming: it completes clean, and the
backticked /proc/<pid>/exe follows the same pattern as the existing <pkg>/<token> in arch.md and
automation.md, which MDX leaves alone inside inline code.

docs-site/content/docs/bazzite.md

@@ -195,6 +195,16 @@ bash /usr/share/punktfunk/bazzite/kde-desktop-setup.sh
 
 Gaming Mode needs none of this — it auto-attaches.
 
+> **Version 0.26.0-1 cannot stream the Desktop, and nothing on this page fixes it.** Every session
+> ends with `KWin does not expose zkde_screencast_unstable_v1 to this client`. That image gave the
+> host binary the `CAP_SYS_NICE` capability, and Linux will not let KWin read the `/proc/<pid>/exe`
+> it uses to work out which program is asking — so the grant above can never match, however
+> correctly it is installed. Reinstalling does not help: it looks like a missing `.desktop` file and
+> is not one. The image's `/usr` is read-only, so it cannot be repaired on the box — take the next
+> image with `sudo punktfunk-sysext update`, then
+> `systemctl --user restart punktfunk-host`. Gaming Mode is unaffected; gamescope has no such
+> identity check.
+
 ## Run as an always-on host
 
 Bazzite hosts are typically headless. Enable the host service and linger so it starts at boot — see