docs: add cPanel section; drop the outbound-filtering page

Adds a cPanel hosting section so cPanel customers have a correct
destination — previously this KB was WHP-only, so cPanel-specific
articles had nowhere to redirect to:

- cpanel/nameservers                        (WHMCS 5, 24k views)
- cpanel/free-ssl-certificate               (WHMCS 8, 18k views)
- cpanel/fix-a-403-error                    (WHMCS 6, 20k views)
- cpanel/wordpress-email-from-your-domain   (WHMCS 7, 25k views)

Rewritten rather than copied where the originals were wrong or thin:
- WordPress SMTP told customers to use port 25 unencrypted; now 587/TLS
  with 465 as the implicit-TLS alternative.
- The 403 article now says explicitly that loosening permissions to 777
  makes suEXEC refuse harder, since that's the instinctive wrong fix.
- AutoSSL gained the actual failure modes (CAA records, .htaccess
  redirects intercepting validation, domain not added to the account).

Also removes email/outbound-spam-filtering, added in the previous commit.
Outbound filtering via Baruwa has been disabled and Baruwa is being retired,
so the page describes a feature we no longer offer. It needs rewriting
around the Proxmox migration before it can ship.

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

src/content/docs/cpanel/fix-a-403-error.mdx

@@ -0,0 +1,67 @@
+---
+title: Why is my site getting a 403 error?
+description: A 403 Forbidden on cPanel hosting is almost always file permissions or file ownership. Here's how to check and fix both.
+sidebar:
+  order: 3
+---
+
+import { Steps, Aside } from '@astrojs/starlight/components';
+import Support from '~/content/partials/support-link.mdx';
+
+A **403 Forbidden** means the web server found your file but refused to serve it. On our cPanel servers that's nearly always one of two things: permissions that are wrong, or files owned by the wrong user.
+
+We run **suEXEC**, which makes your site's code run as *your* account rather than a shared web-server user. That's a security benefit — one account can't read another's files — but it does mean the server is strict about ownership and permissions.
+
+## The correct values
+
+| Item | Permissions |
+| --- | --- |
+| Folders | `755` |
+| Files | `644` |
+
+Anything **more permissive** (a folder at `777`, a file at `666`) is refused by suEXEC. This surprises people, because loosening permissions is the instinctive fix for a permissions error — here it makes things worse, and it's a genuine security risk.
+
+## Fixing it in cPanel
+
+The File Manager handles this without needing a terminal:
+
+<Steps>
+
+1. Sign in to cPanel and open **File Manager**.
+
+2. Navigate to the site's folder. For your primary domain that's normally `public_html`.
+
+3. Select the folder or file, then click **Permissions** in the toolbar.
+
+4. Set folders to `755` and files to `644`. To apply to everything beneath a folder at once, tick the **recurse into subdirectories** option and choose whether it applies to files or folders — you'll need one pass for each, since they take different values.
+
+</Steps>
+
+## When ownership is the problem
+
+Permissions are only half of it. Files also have to be owned by your account.
+
+- **Uploaded over FTP or SFTP?** Ownership is almost certainly fine — the files were created as you.
+- **Pulled the site down over SSH** with `git clone`, `wget`, `curl`, or unpacked an archive as another user? Ownership may be wrong, and no amount of `chmod` will fix that. The files need `chown` back to your account.
+
+If you suspect ownership, [open a ticket](https://secure.anhonesthost.com/submitticket.php) — it's a one-command fix from our side and safer than guessing.
+
+<Aside type="caution">
+  Be careful with recursive commands over SSH. A `chmod -R 777` or a `chown` aimed at the wrong path can break your whole account, and in the case of `777` will leave the site returning 403 anyway. If you aren't confident, ask us.
+</Aside>
+
+## If permissions and ownership are both correct
+
+Other causes of a 403:
+
+- **No index file.** A folder with no `index.html` or `index.php`, on a server with directory listing disabled, returns 403.
+- **An `.htaccess` rule** denying access — either one you added, or one a security plugin wrote.
+- **A security plugin or firewall** blocking your IP after failed logins. Try from a different network or your phone on mobile data; if that works, it's an IP block.
+
+## Related
+
+- [Get your free SSL certificate](/cpanel/free-ssl-certificate/)
+
+## Still stuck?
+
+<Support />