Bake mempalace-toolkit wrappers into the image

The scheduler templates in mempalace-toolkit's contrib/ assume
mempalace-session is available inside the container, but the image
never actually installed it. Users following the *-devbox scheduler
docs would silently lose the wrappers on every container recreate,
because the only way to get them was a post-hoc install.sh inside
the container — which lives in the ephemeral layer. The host-side
systemd timer would then fire, docker exec in, and hit
"mempalace-session: command not found".

Caught during runtime validation on 2026-04-30: host-side systemd
unit ran cleanly at 16:15 today, then the container was rebuilt
and recreated, and the wrappers were gone. The rebuild produced
an image that the scheduler template's own documented precondition
did not hold for.

Fix: new Dockerfile block clones mempalace-toolkit at build time
(depth-1) to /opt/mempalace-toolkit/, symlinks bin/mempalace-session
and bin/mempalace-docs into /usr/local/bin/, asserts both respond
to --help before the layer succeeds. Gated by
INSTALL_MEMPALACE_TOOLKIT=true (defaults on, depends on
INSTALL_MEMPALACE=true). Floated ref via MEMPALACE_TOOLKIT_REF=main
for auto-picking-up toolkit updates; override for reproducible
builds once the toolkit starts tagging releases.

Smoke test gains three assertions (mempalace-session --help,
mempalace-docs --help, symlink target check). Resolved-versions
preamble logs the toolkit git short-SHA alongside the other
floated components, so CI logs always record what got baked in.

README gains a Scheduled mining (mempalace-toolkit) subsection
and a build-args row. DOCKER_HUB.md regenerated; sync-check passes.

README.md

@@ -339,6 +339,7 @@ docker compose build --build-arg NVIM_VERSION=0.12.1   # pin to a specific versi
 |---|---|---|
 | `INSTALL_GO` | `false` | Go toolchain (resolves latest stable from go.dev when `GO_VERSION=latest`) |
 | `INSTALL_MEMPALACE` | `true` | [MemPalace](https://github.com/MemPalace/mempalace) local AI memory system (~300 MB — disable to shrink image if you don't need MCP memory) |
+| `INSTALL_MEMPALACE_TOOLKIT` | `true` | [mempalace-toolkit](https://gitea.jordbo.se/joakimp/mempalace-toolkit) bash wrappers (`mempalace-session`, `mempalace-docs`). Cloned at build time from `MEMPALACE_TOOLKIT_REF` (default `main`). Requires `INSTALL_MEMPALACE=true`. |
 | `INSTALL_OMOS` | `false` | [oh-my-opencode-slim](https://github.com/alvinunreal/oh-my-opencode-slim) multi-agent orchestration (installs Bun and plugin) |
 | `OPENCODE_VERSION` | *(pinned per release)* | opencode npm version. Drives the image tag and is intentionally not floated. |
 | `NODE_VERSION` | `22` | Node.js major version. Pinned to protect against upstream breaking changes across majors. |
@@ -502,6 +503,24 @@ mempalace wake-up
 
 Each workspace gets its own isolated "wing" — memories never leak between projects.
 
+### Scheduled mining (mempalace-toolkit)
+
+The image bakes in [mempalace-toolkit](https://gitea.jordbo.se/joakimp/mempalace-toolkit), a small set of bash wrappers that pair with mempalace for two common routines:
+
+```bash
+# Mine opencode session history (reads ~/.local/share/opencode/opencode.db, stages JSONL, mines into wing_conversations)
+mempalace-session
+
+# Mine a project's docs into a dedicated wing
+mempalace-docs /workspace/my-project
+```
+
+Both wrappers are idempotent and dedup-aware — re-running them on unchanged input is a cheap no-op.
+
+For weekly automated runs, the toolkit ships ready-to-use scheduler templates (systemd user timer, launchd user agent, cron) in its [`contrib/`](https://gitea.jordbo.se/joakimp/mempalace-toolkit/src/branch/main/contrib) directory. The `*-devbox` variants are designed for this container: host-side schedulers that `docker exec` into the running opencode-devbox.
+
+Disable the toolkit (keeps mempalace itself) with `--build-arg INSTALL_MEMPALACE_TOOLKIT=false`. Pin to a specific ref with `--build-arg MEMPALACE_TOOLKIT_REF=v0.3.0` once tagged releases exist.
+
 ### Storage
 
 Two separate named volumes keep different data classes apart: