docs: port still-relevant WHMCS KB articles to the dedicated KB

First step of retiring the WHMCS knowledgebase in favour of
kb.anhonesthost.com. Ports the four articles that are still accurate and
product-agnostic, into three new top-level sections:

- domains/  — transferring a domain, flushing a local DNS cache
- email/    — why we filter outbound mail
- support/  — remote support via RustDesk

Content was refreshed rather than copied verbatim:
- RustDesk download links were pinned to 1.3.8; now point at /releases/latest
  (current is 1.4.9). API server switched to https, which the relay serves.
- macOS DNS flush gained the killall mDNSResponder step, without which the
  documented command usually appears to do nothing.
- The nameserver list was deliberately not ported — this KB points customers
  at Dashboard → Server Information instead of hardcoding per-server values.
- Added an anti-social-engineering warning to the remote-support page.

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

src/content/docs/support/remote-support.mdx

@@ -0,0 +1,68 @@
+---
+title: Remote support with RustDesk
+description: Install and configure the RustDesk client so our support team can connect to your device and help directly.
+sidebar:
+  order: 1
+---
+
+import { Steps, Aside } from '@astrojs/starlight/components';
+import Support from '~/content/partials/support-link.mdx';
+
+Sometimes the fastest way to sort something out is for us to see your screen — configuring an email client, reproducing an error we can't recreate from our side, or walking through a setting together.
+
+We use **RustDesk**, an open-source remote-desktop tool, running on our own relay server rather than a third-party service. Nothing is installed permanently and nothing runs in the background: you start it when you want help and close it when you're done.
+
+<Aside type="caution">
+  We will never ask you to install remote-support software out of the blue. If someone contacts you claiming to be from AnHonestHost and asks for remote access to your computer — especially about a payment, a refund, or a "problem with your account" — stop and [open a ticket](https://secure.anhonesthost.com/submitticket.php) to check it's really us. Only ever run this at the end of a conversation *you* started with us.
+</Aside>
+
+## Install the client
+
+Download RustDesk for your device from the official releases:
+
+- **Windows, macOS, and Android** — [github.com/rustdesk/rustdesk/releases/latest](https://github.com/rustdesk/rustdesk/releases/latest). Pick the `.msi` for Windows, the `.dmg` for macOS, or the signed `.apk` for Android.
+- **iOS / iPadOS** — [RustDesk on the App Store](https://apps.apple.com/us/app/rustdesk-remote-desktop/id1581225015).
+
+## Point it at our server
+
+We run our own ID and relay server, which is faster and keeps your session off shared public infrastructure. You only need to do this once.
+
+<Steps>
+
+1. Open **Settings**. On desktop that's the **three dots** next to your ID; on mobile it's the settings icon.
+
+2. On desktop, choose **Network**. (On mobile, skip straight to the next step.)
+
+3. Choose **ID/Relay server** and enter:
+
+   | Field | Value |
+   | --- | --- |
+   | **ID server** | `rustdesk.cloud-hosting.io` |
+   | **Relay server** | `rustdesk.cloud-hosting.io` |
+   | **API server** | `https://rustdesk.cloud-hosting.io` |
+   | **Key** | `UmpkeFe76AKt8vw8Pj0YCSbxIcYLsqqfPGYzLRl+PgA=` |
+
+4. **Save**, then go back to the **Home** screen.
+
+</Steps>
+
+## Starting a session
+
+The support operator needs two things from the Home screen:
+
+- **Your ID** — a nine-digit number that stays the same for your device.
+- **Your one-time password** — shown beneath the ID, and regenerated each time.
+
+Give both to your support operator over the phone, or in your ticket.
+
+<Aside type="tip">
+  If you send them in a ticket rather than over the phone, **leave your computer on with RustDesk running** — the one-time password only works while the client is open, and we can't connect to a sleeping machine.
+</Aside>
+
+## Ending a session
+
+Close the RustDesk window when you're finished. With it closed, no connection is possible — the one-time password from your session is already spent, and a new one is generated next time you open it. You can uninstall the client entirely if you'd rather.
+
+## Still stuck?
+
+<Support />