feat(systemd): auto-start tmux main session at login and add dotfiles restore unit

config/systemd/user/default.target.wants/tmux-main.service

@@ -0,0 +1 @@
+../tmux-main.service

config/systemd/user/home-dotfiles-restore.service

@@ -0,0 +1,6 @@
+[Unit]
+Description=Restore dotfiles into home directory
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/stow --dotfiles --dir=/home/sjb/.local/share/dotfiles --restow packages apps config

config/systemd/user/tmux-main.service

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+[Unit]
+Description=Ensure tmux session "main" is running
+After=graphical-session.target
+PartOf=graphical-session.target
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=%h/.local/share/dotfiles/script/tmux-start.sh
+# If the session check fails (no server / lost session), retry until login ends.
+Restart=on-failure
+RestartSec=5
+
+[Install]
+WantedBy=default.target

script/tmux-start.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+# Start (or reuse) the tmux server with a session named "main".
+# Used by the tmux-main systemd user service at graphical login.
+#
+# Designed to survive Restart=on-failure: if a session already exists this
+# script reattaches nothing and exits 0; if the server dies systemd restarts
+# us and we recreate the session.
+set -u
+
+session=main
+
+if ! tmux ls 2>/dev/null | grep -q "^${session}:"; then
+  tmux new-session -d -s "$session"
+fi
+
+# Keep the unit "active" only briefly; the session lives in the tmux server.
+exit 0