Add container deployment: Dockerfile, compose, systemd unit, redeploy script

Multi-stage build (node -> go -> alpine) producing the static tefterd
binary with the frontend embedded. Compose follows the house style for
the podman/SELinux server (:Z volume label + label:disable). deploy/
holds the user systemd unit and redeploy-tefter.sh, mirroring the
apelacija setup.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,20 @@
+services:
+  tefter:
+    build:
+      context: .
+      args:
+        VERSION: ${TEFTER_VERSION:-dev}
+    environment:
+      TEFTER_DB: /data/tefter.db
+    volumes:
+      # ":Z" relabels for SELinux (required on the podman/SELinux server; a
+      # harmless no-op on non-SELinux Docker hosts).
+      - data:/data:Z
+    security_opt:
+      - label:disable
+    ports:
+      - "${WEB_PORT:-8420}:8420"
+    restart: unless-stopped
+
+volumes:
+  data: