Initial commit: arr-stack homelab + local AI

Docker Compose media stack (gluetun, *arr, Jellyfin), Ternary-Bonsai AI
(Open WebUI, Forgejo, optional OpenHands), and Ansible bootstrap for the
SER5 Ubuntu host.

docker-compose.override.yml

@@ -0,0 +1,22 @@
+# GPU access for Vulkan (bonsai) + VA-API (jellyfin).
+#
+# Do NOT use group names like "video"/"render" here — Docker resolves them
+# inside the container image, which often has no "render" group and fails with:
+#   unable to find group render: no matching entries in group file
+#
+# Options:
+#   A) Rely on host /dev/dri being 0666 (Ansible users role udev rule) — no group_add.
+#   B) Use numeric host GIDs:  getent group video render
+#
+# Ansible regenerates this file with host GIDs when you run the stack role.
+
+services:
+  bonsai:
+    devices:
+      - /dev/dri:/dev/dri
+    environment:
+      NGL: "99"
+
+  jellyfin:
+    devices:
+      - /dev/dri:/dev/dri