wiki: add Plex 4K codec guide and mdadm USB recovery; update yt-dlp, indexes

New articles:
- 04-streaming/plex/plex-4k-codec-compatibility.md
- 05-troubleshooting/storage/mdadm-usb-hub-disconnect-recovery.md

Updated:
- yt-dlp.md: Plex section and config reflect new HEVC auto-convert workflow
- SUMMARY.md, index.md, README.md, section indexes: 39 → 41 articles
- MajorWiki-Deploy-Status.md: count + date

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

MajorWiki-Deploy-Status.md

@@ -31,7 +31,7 @@ DNS record and Caddy entry have been removed.
 
 ## Content
 
-- 39 articles across 5 domains
+- 41 articles across 5 domains
 - Source of truth: `MajorVault/20-Projects/MajorTwin/08-Wiki/`
 - Deployed via Gitea webhook (push from MajorAir → auto-pull on majorlab)
 
@@ -63,7 +63,7 @@ rsync -av --include="*.md" --include="*/" --exclude="*" \
 
 ---
 
-*Updated 2026-03-14*
+*Updated 2026-03-15*
 
 ## Canonical Update Workflow