initial: gitea-bot — mochi 全站 issue/PR 自动处理

systemd --user unit, polls famzheng.me/gitea every 60s, dispatches
`claude --dangerously-skip-permissions -p ...` per new activity.
sqlite state, log to ~/.local/state/gitea-bot/bot.log.

gitea-bot.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=gitea-bot — mochi 全站 issue/PR 自动处理
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/python3 /home/fam/src/gitea-bot/bot.py
+Restart=on-failure
+RestartSec=15
+# claude / git / curl / node 等都在 PATH 里
+Environment=PATH=/home/fam/.local/bin:/home/fam/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+Environment=HOME=/home/fam
+StandardOutput=append:/home/fam/.local/state/gitea-bot/bot.log
+StandardError=append:/home/fam/.local/state/gitea-bot/bot.log
+
+[Install]
+WantedBy=default.target