docs: fact-check sweep, Jellyfin, *arr stack, and ROM scraping guides

Fact-check results:
- RomM 5.2.0: MariaDB+Redis now required (was SQLite), auth var renamed, 11 metadata providers
- Copyparty v1.20.19: 3 CVEs fixed, WOPI integration, docker editions documented
- Calibre-Web 0.6.27-ls397: version pinning, kepubify auto-config, CVE fixes
- Calibre 9.9.0: content server security fix noted

New documentation:
- docs/Dankserver/Jellyfin.md — full media server guide (compose, Caddy, GPU, metadata, clients)
- docs/Dankserver/ARR-Stack.md — automated download stack overview
- docs/Dankserver/RomM-Scraping.md — metadata providers, naming, cover art, emulator integration
- docs/Dankserver/sonarr.md, radarr.md, lidarr.md, readarr.md, prowlarr.md, qbittorrent.md
- docs/Dankserver/mariadb.md, redis.md — supporting services for RomM

Infrastructure updates:
- dankserver/compose.yaml: added mariadb, redis, jellyfin, *arr services
- dankserver/Caddyfile: added hostnames for all new services
- dankserver/.env.example: added all new environment variables
- docs/index.md: linked all new documentation pages

Tested: 52/52 tests pass.

dankserver/Caddyfile

@@ -1,7 +1,6 @@
 # Dankserver Caddyfile
-# Migrated from the live /etc/caddy/Caddyfile on dankserver, extended with the
-# new stack services. Native caddy (systemd) on this host; upstreams are host
-# ports because the services publish to the host.
+# Deploy: copy to /etc/caddy/Caddyfile on dankserver
+# See ../docs/Dankserver/ for service documentation.
 
 {
 	admin off
@@ -54,3 +53,47 @@ files.dankserver.local {
 	}
 	reverse_proxy localhost:3923
 }
+
+# --- Jellyfin ---
+jellyfin.dankserver.local {
+	reverse_proxy 127.0.0.1:8096
+
+	transport http {
+		versions h2c 1.1
+	}
+}
+
+# --- *arr Stack ---
+radarr.dankserver.local {
+	reverse_proxy localhost:7878
+}
+
+sonarr.dankserver.local {
+	reverse_proxy localhost:8989
+}
+
+lidarr.dankserver.local {
+	reverse_proxy localhost:8686
+}
+
+readarr.dankserver.local {
+	reverse_proxy localhost:8787
+}
+
+prowlarr.dankserver.local {
+	reverse_proxy localhost:9696
+}
+
+qbittorrent.dankserver.local {
+	reverse_proxy localhost:8080
+}
+
+# --- Optional: Jackett ---
+# jackett.dankserver.local {
+# 	reverse_proxy localhost:9117
+# }
+
+# --- Optional: Whisparr ---
+# whisparr.dankserver.local {
+# 	reverse_proxy localhost:6969
+# }