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>

.dockerignore

@@ -0,0 +1,10 @@
+.git
+.gitea
+build
+desktop
+frontend/node_modules
+frontend/dist
+server/webdist/dist
+notes.zip
+*.md
+.env.docker