docs: link every client in the clients-page chooser + correctness sweep

The "Which should I use?" table on the clients page listed most client
names as bold text, not links — only the Decky plugin and pf-webos were
clickable — so the client references appeared broken. Link each client to
its section (or dedicated page), and fix a stale Windows headless command.

Repo-wide docs correctness/staleness pass against the code:
- steam-deck: client-not-found -> flatpak-not-found (the real backend code)
- install: host cert is punktfunk-host-windows_<ver>.cer, not ..._setup.cer
- configuration: GPU_PRIORITY_CLASS default is auto; 10BIT/444 are default-on
- how-it-works/index: GameStream/Moonlight is opt-in (--gamestream)
- roadmap: clipboard sync is shipped, not planned
- install-client: MSIX/cert artifacts are arch-suffixed (_x64/_arm64)
- requirements: fix garbled 22H2/IddCx sentence
- status: Linux encode also covers AMD/Intel (VAAPI/Vulkan Video)
- automation: add the plugins.changed event
- windows-host: note the optional bundled VB-CABLE virtual mic
- sway: PUNKTFUNK_COMPOSITOR=hyprland is a wlroots-family alias
- running-as-a-service: punktfunk-probe is a source-build-only dev tool

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

docs-site/content/docs/index.mdx

@@ -18,9 +18,9 @@ It's built for the things that make streaming feel native:
   plug to deal with, even on the secure desktop.
 - **Low latency, GPU end to end.** Frames go straight from the compositor to the GPU encoder
   (NVENC) with zero CPU copies, and over a transport tuned for responsiveness rather than throughput.
-- **Works with the apps you already have.** punktfunk speaks the GameStream protocol, so any
-  **Moonlight** client connects out of the box — and a faster **native protocol** with dedicated apps
-  for **macOS, iOS, tvOS, Linux, Windows, and Android**.
+- **Works with the apps you already have.** punktfunk also speaks the GameStream protocol, so with
+  `--gamestream` any **Moonlight** client connects — alongside a faster **native protocol** with
+  dedicated apps for **macOS, iOS, tvOS, Linux, Windows, and Android**.
 - **Secure by default.** Hosts require a one-time PIN pairing; after that, devices reconnect on a
   pinned identity. No accounts, no cloud.