Implement r5500 media stack configuration with NFS and Docker services

- Added configuration for media stack on r5500, including paths for Jellyfin, Sonarr, Radarr, and other media services.
- Integrated NFS client for accessing Jellyfin libraries from nixdesk.
- Established Docker services for Dispatcharr and Organizr, including necessary user and group setups.
- Created systemd services for managing media directories and ensuring proper permissions.

modules/hosts/r5500/_private/media-disk.nix

@@ -0,0 +1,52 @@
+# Media stack storage on r5500: btrfs subvolume @media-stack on the OS disk (sda4).
+{ config, pkgs, lib, ... }:
+let
+  btrfsUuid = "934a5ec3-4bab-49c3-96c9-c857c50076ba";
+  btrfsDevice = "/dev/disk/by-uuid/${btrfsUuid}";
+  # Created under subvol=@ → full path is @/@media-stack (not a top-level @media-stack).
+  mediaSubvol = "@/@media-stack";
+in
+{
+  # Create @media-stack before /mnt/media-stack is mounted.
+  systemd.services.r5500-media-stack-subvolume = {
+    description = "Create btrfs subvolume @media-stack on sda4 if missing";
+    before = [ "mnt-media\\x2dmedia\\x2dstack.mount" ];
+    wantedBy = [ "local-fs-pre.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+    script = ''
+      rootMount="/mnt/.r5500-btrfs-root"
+      mkdir -p "$rootMount"
+      if ! mountpoint -q "$rootMount"; then
+        mount -o subvol=@ "${btrfsDevice}" "$rootMount"
+        umountAfter=1
+      else
+        umountAfter=0
+      fi
+      if ! ${pkgs.btrfs-progs}/bin/btrfs subvolume show "$rootMount/@media-stack" >/dev/null 2>&1; then
+        ${pkgs.btrfs-progs}/bin/btrfs subvolume create "$rootMount/@media-stack"
+      fi
+      if [ "$umountAfter" -eq 1 ]; then
+        umount "$rootMount"
+      fi
+    '';
+  };
+
+  # Optional 1 TiB cap (run once after first boot if desired):
+  #   sudo btrfs quota enable /mnt/media-stack && sudo btrfs qgroup limit 1T /mnt/media-stack
+
+  fileSystems."/mnt/media-stack" = {
+    device = btrfsDevice;
+    fsType = "btrfs";
+    neededForBoot = false;
+    options = [
+      "subvol=${mediaSubvol}"
+      "compress=zstd"
+      "noatime"
+      "nofail"
+      "x-systemd.device-timeout=30"
+    ];
+  };
+}

modules/hosts/r5500/_private/media-paths.nix

@@ -0,0 +1,70 @@
+# Shared media group, directory layout, and Jellyfin config bind-mount on /mnt/media-stack.
+{ config, lib, pkgs, ... }:
+let
+  paths = import ./media-stack-paths.nix;
+  prowlarrCustomIndexer = "${./../_services/prowlarr/torrent9-custom.yml}";
+  inherit (paths)
+    mediaRoot
+    downloadsDir
+    downloadsIncompleteDir
+    sonarrDataDir
+    radarrDataDir
+    prowlarrDataDir
+    qbittorrentDataDir
+    seerrConfigDir
+    dispatcharrDataDir
+    organizrDataDir
+    jellyfinConfigDir
+    jellyfinMoviesDir
+    jellyfinTvDir
+    ;
+in
+{
+  _module.args.mediaStackPaths = paths;
+
+  users.groups.media = { };
+
+  users.users.server.extraGroups = [ "media" ];
+
+  # Layout dirs only after /mnt/media-stack is mounted (tmpfiles at early boot would
+  # otherwise create paths on the root fs and break bind mounts / boot).
+  systemd.services.r5500-media-stack-dirs = {
+    description = "Create media-stack directory layout";
+    after = [ "mnt-media\\x2dmedia\\x2dstack.mount" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+    script = ''
+      set -e
+      install -d -m 0775 -o root -g media ${mediaRoot}
+      install -d -m 2775 -o root -g media ${jellyfinMoviesDir} ${jellyfinTvDir} ${downloadsDir}
+      install -d -m 2775 -o root -g media ${downloadsIncompleteDir}
+      install -d -m 0755 -o jellyfin -g jellyfin ${jellyfinConfigDir}
+      install -d -m 0700 -o sonarr -g sonarr ${sonarrDataDir}
+      install -d -m 0700 -o radarr -g radarr ${radarrDataDir}
+      install -d -m 0700 -o prowlarr -g prowlarr ${prowlarrDataDir}
+      install -d -m 0750 -o qbittorrent -g qbittorrent ${qbittorrentDataDir}
+      install -d -m 0755 -o jellyseerr -g jellyseerr ${seerrConfigDir} 2>/dev/null \
+        || install -d -m 0755 -o root -g root ${seerrConfigDir}
+      install -d -m 0777 -o root -g root ${dispatcharrDataDir}
+      install -d -m 0755 -o organizr -g organizr ${organizrDataDir} 2>/dev/null \
+        || install -d -m 0755 -o root -g root ${organizrDataDir}
+      install -d -m 0700 -o prowlarr -g prowlarr ${prowlarrDataDir}/Definitions/Custom
+      ln -sfn ${prowlarrCustomIndexer} ${prowlarrDataDir}/Definitions/Custom/torrent9-custom.yml
+    '';
+  };
+
+  # Jellyfin metadata on the media subvolume; nofail so a missing subvol never bricks boot.
+  fileSystems."/var/lib/jellyfin" = {
+    device = jellyfinConfigDir;
+    fsType = "none";
+    neededForBoot = false;
+    options = [
+      "bind"
+      "nofail"
+      "x-systemd.after=mnt-media\\x2dmedia\\x2dstack.mount"
+    ];
+  };
+}

modules/hosts/r5500/_private/media-stack-paths.nix

@@ -0,0 +1,16 @@
+# Path constants for the r5500 media stack (imported by _services/* and media-paths.nix).
+{
+  mediaRoot = "/mnt/media-stack";
+  downloadsDir = "/mnt/media-stack/downloads";
+  downloadsIncompleteDir = "/mnt/media-stack/downloads/incomplete";
+  sonarrDataDir = "/mnt/media-stack/sonarr";
+  radarrDataDir = "/mnt/media-stack/radarr";
+  prowlarrDataDir = "/mnt/media-stack/prowlarr";
+  qbittorrentDataDir = "/mnt/media-stack/qbittorrent";
+  seerrConfigDir = "/mnt/media-stack/seerr";
+  dispatcharrDataDir = "/mnt/media-stack/dispatcharr";
+  organizrDataDir = "/mnt/media-stack/organizr";
+  jellyfinConfigDir = "/mnt/media-stack/jellyfin/config";
+  jellyfinMoviesDir = "/mnt/media-stack/jellyfin/movies";
+  jellyfinTvDir = "/mnt/media-stack/jellyfin/tv";
+}