Add teabot daemon implementation

teabot watches Gitea repos and dispatches one-shot Claude Code sessions in
Docker containers to work issues and review PRs, acting as configurable bot
personalities.

Claude-Session: https://claude.ai/code/session_015ur3i7D2azsMAWTSVABApv

systemd/teabot.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=teabot - Gitea watcher dispatching one-shot Claude Code sessions
+Documentation=https://git.unkin.net/unkin/teabot
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+# Run in the foreground; teabot logs to stderr which the journal captures.
+ExecStart=/usr/bin/teabot run
+Restart=on-failure
+RestartSec=10
+# teabot shells out to docker; keep the user's environment (PATH, DOCKER_HOST).
+Environment=XDG_CONFIG_HOME=%h/.config
+Environment=XDG_STATE_HOME=%h/.local/state
+
+[Install]
+WantedBy=default.target