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/how-it-works.md

@@ -43,15 +43,15 @@ GPU path** that keeps latency low even at high resolutions and frame rates.
 
 punktfunk speaks two protocols over the same host:
 
-- **GameStream** — the protocol Moonlight uses. Any [Moonlight](/docs/moonlight) client connects with
-  no special software. This is the most compatible way in.
+- **GameStream** — the protocol Moonlight uses. Start the host with `--gamestream` and any
+  [Moonlight](/docs/moonlight) client connects with no special software. This is the most compatible way in.
 - **punktfunk/1 (native)** — a purpose-built protocol with a QUIC control channel and a UDP data
   channel hardened with forward error correction and encryption. It's lower-latency and more resilient
   on imperfect networks, and it's what the [native clients](/docs/clients) (Apple, Linux, Windows,
   Android) use.
 
-Both run from a single host process, so you don't choose up front — Moonlight clients use GameStream,
-the native clients use punktfunk/1.
+The native `punktfunk/1` plane runs by default (the secure default); add `--gamestream` and both planes
+serve from a single host process — Moonlight clients use GameStream, the native clients use punktfunk/1.
 
 ## Pairing and trust