feat: host-agnostic LAN access (base) + fork/recall in pi variants

Item A — LAN access (base image):
- New rootfs/usr/local/lib/opencode-devbox/setup-lan-access.sh, invoked
  non-fatally from entrypoint-user.sh. On VM-backed hosts (macOS OrbStack /
  Docker Desktop, detected via host.docker.internal) it generates a writable
  ~/.ssh-local/config that uses the host as an SSH jump to reach LAN peers;
  no-op on native Linux. Ships the mechanism (generic 'host' jump alias),
  not policy (targets stay in the user's bind-mounted ~/.ssh/config).
- New env knobs: DEVBOX_LAN_ACCESS (auto|jump|off), HOST_SSH_USER,
  DEVBOX_HOST_ALIAS. dssh/dscp aliases in .bash_aliases (guarded).

Item B — pi-fork (fork) + pi-observational-memory (recall) in pi variants:
- Dockerfile.variant clones both elpapi42 repos to /opt and runs npm install
  there at build time (local-path 'pi install' does not npm-install, so deps
  must be present to load). New args PI_FORK_REPO/REF, PI_OBSMEM_REPO/REF.
- entrypoint-user.sh registers them at runtime via 'pi install /opt/<pkg>'
  (instant, in-place, idempotent; tools bind on next pi start).
- CI resolve-versions resolves each repo's master HEAD to a commit SHA and
  passes PI_FORK_REF/PI_OBSMEM_REF — same cache-hit guard as PI_VERSION.
- smoke-test asserts /opt clones + node_modules + settings.json registration;
  size thresholds bumped (with-pi 2700->2900, omos-with-pi 3700->3900).

Versions unchanged (opencode 1.15.13, pi 0.78.0 — both still latest).
Docs: README LAN section + env table, .env.example, AGENTS.md, CHANGELOG.
Plan recorded in docs/plan-lan-access-and-pi-extensions.md.

AGENTS.md

@@ -7,9 +7,10 @@ Docker image packaging [opencode](https://opencode.ai) into a production-ready d
 ## File roles
 
 - `Dockerfile.base` — variant-independent layers (apt, locales, AWS CLI, Node.js, mempalace, gitea-mcp, user setup, chromadb prewarm, ENVs, entrypoints). Published as `joakimp/opencode-devbox:base-<sha12>`. Rebuilt only when its content hash changes.
-- `Dockerfile.variant` — `FROM`s the base and adds only opencode/omos/pi installs gated by build args: `INSTALL_OPENCODE` (default true), `INSTALL_OMOS`, `INSTALL_PI`, and `INSTALL_MEMPALACE`. All GitHub-sourced binaries are pinned with version ARGs.
+- `Dockerfile.variant` — `FROM`s the base and adds only opencode/omos/pi installs gated by build args: `INSTALL_OPENCODE` (default true), `INSTALL_OMOS`, `INSTALL_PI`, and `INSTALL_MEMPALACE`. All GitHub-sourced binaries are pinned with version ARGs. When `INSTALL_PI=true` it also clones `pi-fork` + `pi-observational-memory` (from `github.com/elpapi42`, refs `PI_FORK_REF`/`PI_OBSMEM_REF`) to `/opt` and runs `npm install` there at build time so the `fork`/`recall` extensions can load (a local-path `pi install` does not npm-install).
 - `entrypoint.sh` — runs as root: UID/GID adjustment, SSH permissions, volume ownership fixes (skipped via `.devbox-owner` sentinel when ownership is already correct). Then drops to developer via gosu. Volume ownership loop covers `~/.pi/` when `INSTALL_PI=true`.
-- `entrypoint-user.sh` — runs as developer: git config, opencode.jsonc generation (delegated to `generate-config.py`), pi-toolkit + pi-extensions deploy (when pi installed), pi settings.json bootstrap, mempalace pi-bridge symlink, skillset auto-deploy from mounted skillset repo, OMOS setup.
+- `entrypoint-user.sh` — runs as developer: git config, opencode.jsonc generation (delegated to `generate-config.py`), LAN-access setup (delegated to `setup-lan-access.sh`), pi-toolkit + pi-extensions deploy (when pi installed), pi settings.json bootstrap, mempalace pi-bridge symlink, runtime `pi install /opt/{pi-fork,pi-observational-memory}` registration (idempotent), skillset auto-deploy from mounted skillset repo, OMOS setup.
+- `rootfs/usr/local/lib/opencode-devbox/setup-lan-access.sh` — host-OS-agnostic LAN reachability helper. Detects VM-backed hosts (macOS OrbStack / Docker Desktop, via `host.docker.internal` resolution) and generates a writable `~/.ssh-local/config` using the host as an SSH jump; no-op on native Linux. Controlled by `DEVBOX_LAN_ACCESS` / `HOST_SSH_USER` / `DEVBOX_HOST_ALIAS`. Ships the mechanism only (generic `host` jump alias); user targets stay in their bind-mounted `~/.ssh/config`. Non-fatal. Counted in the base hash, so editing it advances `base-latest`.
 - `rootfs/usr/local/lib/opencode-devbox/generate-config.py` — generates `~/.config/opencode/opencode.jsonc` from env vars. Never overwrites an existing config (checks both `.json` and `.jsonc`). Auto-registers MCP servers for detected tools (mempalace via `mempalace-mcp`, gitea-mcp, context7 remote endpoint).
 - `scripts/smoke-test.sh` — post-build image verification. Asserts binary presence, opencode startup, entrypoint correctness, config generation idempotency, and image size thresholds. Used by both CI workflows.
 - `scripts/generate-dockerhub-md.py` — generates `DOCKER_HUB.md` from a hand-maintained `HUB_TEMPLATE` constant. `--check` fails if the committed file is out of sync (enforced by the `validate` workflow).