Add Tdarr transcoding manager for bulk H.264→HEVC conversion

Runs Tdarr server with internal node on the mediaserver for managing
library-wide re-encoding to save disk space. Web UI at tdarr.nordhammer.it.

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

common.nix

@@ -31,6 +31,7 @@
     ./services/fail2ban.nix
     ./services/authelia.nix
     ./services/homepage.nix
+    ./services/tdarr.nix
     ./services/arr-interconnect.nix
   ];
 

services/nginx.nix

@@ -103,6 +103,7 @@ in
         # --- Other ---
         "games.nordhammer.it"  = proxy 8787;
         "search.nordhammer.it" = proxy 8087;
+        "tdarr.nordhammer.it"  = proxy 8265;
 
         # --- Protected by Authelia ---
         "camera.nordhammer.it"   = protectedProxy 1984;

services/tdarr.nix

@@ -0,0 +1,48 @@
+# services/tdarr.nix — Tdarr transcoding manager
+{ config, pkgs, lib, ... }:
+{
+  config = lib.mkIf (config.networking.hostName == "FredOS-Mediaserver") {
+
+    systemd.services.tdarr-server = {
+      description = "Tdarr Server";
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+
+      serviceConfig = {
+        Type = "simple";
+        User = "tdarr";
+        Group = "media";
+        StateDirectory = "tdarr";
+        ExecStart = "${pkgs.tdarr-server}/bin/tdarr-server";
+        Restart = "on-failure";
+        RestartSec = 10;
+
+        # Tdarr server config via environment
+        Environment = [
+          "HOME=/var/lib/tdarr"
+          "serverIP=0.0.0.0"
+          "serverPort=8266"
+          "webUIPort=8265"
+          "internalNode=true"
+          "inContainer=false"
+          "ffmpegVersion=6"
+          "nodeName=FredOS-Mediaserver"
+        ];
+      };
+    };
+
+    users.users.tdarr = {
+      isSystemUser = true;
+      group = "media";
+      extraGroups = [ "media" "video" "render" ];
+      home = "/var/lib/tdarr";
+    };
+
+    systemd.tmpfiles.rules = [
+      "d /var/lib/tdarr 0755 tdarr media -"
+      "d /var/lib/tdarr/server 0755 tdarr media -"
+      "d /var/lib/tdarr/configs 0755 tdarr media -"
+      "d /var/lib/tdarr/logs 0755 tdarr media -"
+    ];
+  };
+}