wiki: add firewalld mail ports reset article + session updates

- New article: firewalld mail ports wiped after reload (IMAP + webmail outage)
- New article: Plex 4K codec compatibility (Apple TV)
- New article: mdadm RAID recovery after USB hub disconnect
- Updated yt-dlp article
- Updated all index files: SUMMARY.md, index.md, README.md, category indexes
- Article count: 41 → 42

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

05-troubleshooting/index.md

@@ -8,6 +8,7 @@ Practical fixes for common Linux, networking, and application problems.
 ## 🌐 Networking & Web
 - [Apache Outage: Fail2ban Self-Ban + Missing iptables Rules](networking/fail2ban-self-ban-apache-outage.md)
 - [Mail Client Stops Receiving: Fail2ban IMAP Self-Ban](networking/fail2ban-imap-self-ban-mail-client.md)
+- [firewalld: Mail Ports Wiped After Reload](networking/firewalld-mail-ports-reset.md)
 - [ISP SNI Filtering & Caddy](isp-sni-filtering-caddy.md)
 - [yt-dlp YouTube JS Challenge Fix](yt-dlp-fedora-js-challenge.md)
 
@@ -19,6 +20,9 @@ Practical fixes for common Linux, networking, and application problems.
 ## 🔒 SELinux
 - [SELinux: Fixing Dovecot Mail Spool Context (/var/vmail)](selinux-dovecot-vmail-context.md)
 
+## 💾 Storage
+- [mdadm RAID Recovery After USB Hub Disconnect](storage/mdadm-usb-hub-disconnect-recovery.md)
+
 ## 📝 Application Specific
 - [Obsidian Vault Recovery — Loading Cache Hang](obsidian-cache-hang-recovery.md)
 - [Gemini CLI Manual Update](gemini-cli-manual-update.md)