docs: LAN-access ssh-lan.conf + DEVBOX_LAN_AUTOJUMP_PRIVATE (inherited from base)

setup-lan-access.sh fixes (Include scope, ControlPath) + ssh-lan.conf and
RFC1918 autojump flow in via FROM base-pi-only. Documents the knob and new
host-owned config. Tag v0.78.0c AFTER opencode-devbox v1.15.13d publishes the
rebuilt base-pi-only, so it doesn't build on the stale base.

README.md

@@ -27,7 +27,7 @@ Base tooling:
 - **Gitea MCP** server
 - **Dev tools**: neovim (LazyVim), tmux, bat, eza, fzf, zoxide, ripgrep, jq, git-lfs, make
 - **Shell**: bash with history tuning, prefix-search, fzf/zoxide integration
-- **Host-OS-agnostic LAN access** — on VM-backed hosts (macOS OrbStack / Docker Desktop) the entrypoint sets up the host as an SSH jump so you can reach LAN peers (`dssh` alias; `DEVBOX_LAN_ACCESS`/`HOST_SSH_USER` env). No-op on native Linux.
+- **Host-OS-agnostic LAN access** — on VM-backed hosts (macOS OrbStack / Docker Desktop) the entrypoint sets up the host as an SSH jump so you can reach LAN peers (`dssh` alias; `DEVBOX_LAN_ACCESS` / `HOST_SSH_USER` / `DEVBOX_LAN_AUTOJUMP_PRIVATE` env; host-owned `~/.config/devbox-shell/ssh-lan.conf` for named-peer jumps). No-op on native Linux.
 
 pi and companions:
 
@@ -202,6 +202,7 @@ All config flows through `.env`. The full list (with annotations) is in [`.env.e
 | `GITHUB_PERSONAL_ACCESS_TOKEN` | (unset) | GitHub MCP server / git ops over HTTPS |
 | `DEVBOX_LAN_ACCESS` | `auto` | LAN-access mode: `auto` (jump only on VM-backed hosts), `jump`, `off` |
 | `HOST_SSH_USER` | (unset) | Host username for the LAN SSH jump (see opencode-devbox README) |
+| `DEVBOX_LAN_AUTOJUMP_PRIVATE` | `0` | `1` = ProxyJump any private (RFC1918) IP through the host (roaming-friendly; see opencode-devbox README) |
 | `LANG` / `LANGUAGE` / `LC_ALL` | `en_US.UTF-8` | Locale override |
 
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