docs: USB passthrough is a plugin now, not a recipe you assemble

Adds a VirtualHere section to the plugins page — what it is, that both halves of VirtualHere
are yours to install and licence, that the Devices tab writes a name-based rule so it survives
the couch rebooting, and that Diagnostics is where to look when nothing happens.

States the coverage limit up front rather than letting somebody discover it: there is no
VirtualHere server for iOS or tvOS, so those clients cannot pass devices through, and nothing
on our side can change that.

Cuts the automation.md recipe from 75 lines to a pointer. It now leads with "use the plugin"
and keeps only the zero-code two-hook version for people who would rather not install one —
with its trade-offs stated instead of implied: the address is hard-coded so it breaks when the
couch reboots, and an abnormal stream end strands the device on the host. Those two failures
are exactly what the plugin exists to fix, so the reader gets to make an informed choice.

Not build-verified: docs-site does not build standalone in this checkout. Checked by hand that
Callout is in fumadocs' default MDX components with a valid `warn` type, that the JSX balances,
and that the cross-page anchor matches github-slugger of the heading.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs-site/content/docs/plugins.mdx

@@ -1,18 +1,19 @@
 ---
 title: Plugins
-description: First-party plugins that sync your ROM collection or your Playnite library into the game library — and how to install them.
+description: First-party plugins — sync your ROM collection or Playnite library into the game library, or hand a real USB device on the couch to the host — and how to install them.
 ---
 
 Plugins extend the host through the **scripting runner** (see [Events & hooks](/docs/automation)). A
 plugin runs alongside the host, reconciles titles into your **game library** as a provider — so they
 appear in the grid on every client — and can add its own page to the [web console](/docs/web-console).
 
-Two first-party plugins today:
+Three first-party plugins today:
 
 | Plugin | What it does |
 |---|---|
 | **ROM Manager** | Scans your ROM directories, matches each platform to an installed emulator, and syncs them into the library with box art. |
 | **Playnite** | Mirrors your [Playnite](https://playnite.link) library — every store and emulator it manages — into the library, launched back through Playnite. |
+| **VirtualHere** | Hands a real USB device on the couch — wheel, HOTAS, pad — to the host while you play, and gives it back after. Needs [VirtualHere](https://www.virtualhere.com/), sold separately. |
 
 ## Installing from the console
 
@@ -200,6 +201,48 @@ seconds of any library change. Filters (installed-only, per-store, hidden) live
 `%ProgramData%\punktfunk\playnite\config.json`. Details are in
 [the plugin's repo](https://git.unom.io/unom/punktfunk-plugin-playnite).
 
+## VirtualHere (USB passthrough)
+
+`@punktfunk/plugin-virtualhere` — hands a **physical USB device** on your couch machine to the
+host while you play, and gives it back afterwards. The game sees the real device, so this is the
+answer for a racing wheel, a HOTAS, pedals, an arcade stick, or any controller whose value is that
+it is not emulated.
+
+<Callout type="warn">
+This plugin drives [VirtualHere](https://www.virtualhere.com/), a commercial USB-over-IP product
+**sold separately** by VirtualHere Pty. Ltd. Nothing from VirtualHere is bundled or downloaded by
+Punktfunk — you install and license it yourself. The plugin is not affiliated with or endorsed by
+VirtualHere.
+</Callout>
+
+You need both halves of VirtualHere running before the plugin is any use:
+
+- **The USB Server on the couch**, sharing the device. Free for one device; beyond that, and to run
+  the client as a service, VirtualHere requires a purchased licence.
+- **The USB Client on the host**, ideally installed as a service so it survives logging out.
+
+Servers exist for Windows, Linux, macOS and Android couches. **There is no VirtualHere server for
+iOS or tvOS**, so iPhones, iPads and Apple TVs cannot pass devices through — nothing on the
+Punktfunk side can change that.
+
+```sh
+punktfunk-host plugins add virtualhere
+punktfunk-host plugins enable
+```
+
+Then open the console's **VirtualHere** page. The **Devices** tab lists whatever the couch is
+sharing; pick one and it writes a rule matching the device *by name*, which keeps working after the
+couch reboots or the device moves to another port. By default the device is handed over when video
+starts and returned when it stops, so the couch keeps its own controller the rest of the time —
+you can widen that to the whole session, or to the entire time a client is connected.
+
+If nothing happens, the **Diagnostics** tab walks the whole two-sided setup and tells you which
+part to fix. The same checks are available as `punktfunk-plugin-virtualhere doctor`, which is the
+useful thing to paste into a support thread.
+
+Full configuration is in
+[the plugin's repo](https://git.unom.io/unom/punktfunk-plugin-virtualhere).
+
 ## Troubleshooting
 
 **`punktfunk-host: command not found`** — on Windows, open a new terminal so it picks up the