docs(rootfs): re-sync mempalace snapshot from skillset 63f3bf5

Closes the drift found in 4d4abd9's investigation: the Temporal grounding
guidance was authored straight into this vendored fallback (904fe85) and never
returned to skillset, the declared owner. skillset 63f3bf5 now carries it (with
the wording generalized from "a pi-devbox container" to "a devbox container
(pi-devbox or opencode-devbox)", since opencode-devbox vendors the same skill),
so this snapshot is a pure mirror of the owner again.

VENDORED.md: refresh commands now copy each snapshot FROM ITS OWNER. The
pi-extensions lines previously pointed at <skillset>/skills/pi-extensions/,
which has been a downstream duplicate since a7f3044 co-located the canonical
skill in the package repo — following the old instruction would have silently
regressed the snapshot (e.g. undoing pi-extensions e73cb9f). Provenance bumped
to skillset 63f3bf5 / pi-extensions pkg e73cb9f.

rootfs/usr/local/share/pi-devbox/skills/VENDORED.md

@@ -40,8 +40,14 @@ its skill file needed baking.
 
 ## Refreshing the snapshots
 
-    cp <skillset>/skills/pi-extensions/SKILL.md   pi-extensions/SKILL.md
-    cp <skillset>/skills/pi-extensions/evaluate-extension-usage.py pi-extensions/
+    cp <pi-extensions-pkg>/skill/SKILL.md                    pi-extensions/SKILL.md
+    cp <pi-extensions-pkg>/skill/evaluate-extension-usage.py pi-extensions/
     cp <skillset>/skills/mempalace/SKILL.md                  mempalace/SKILL.md
 
-Snapshot provenance at last refresh: skillset `8e8db64`, pi-extensions pkg `a7f3044`.
+Copy each snapshot **from its owner in the table above** — `pi-extensions` from
+the package repo's `skill/` (since `a7f3044` co-located it there; `skillset`
+also carries a copy, but it is a downstream duplicate and can lag), and
+`mempalace` from `skillset`. Copying `pi-extensions` from `skillset` would
+regress the snapshot to whatever that repo last mirrored.
+
+Snapshot provenance at last refresh: skillset `63f3bf5`, pi-extensions pkg `e73cb9f`.

rootfs/usr/local/share/pi-devbox/skills/mempalace/SKILL.md

@@ -51,12 +51,13 @@ Before describing *when* something happened — "yesterday", "earlier today",
 compute the delta against the actual timestamp.** Get "now" from the injected
 session date or by running `date` in a shell; never infer it.
 
-**A container recreate or a fresh session is NOT a day boundary.** A pi-devbox
-container is frequently restarted — often several times within the *same* day —
-and each restart begins a new session with a fresh wake-up. Do not reason "new
-session ⇒ last session was yesterday": two diary entries 90 minutes apart can
-straddle a container recreate. The only authoritative clock is the timestamp on
-the memory, not the session/container boundary.
+**A container recreate or a fresh session is NOT a day boundary.** A devbox
+container (pi-devbox or opencode-devbox) is frequently restarted — often several
+times within the *same* day — and each restart begins a new session with a fresh
+wake-up. Do not reason "new session ⇒ last session was yesterday": two diary
+entries 90 minutes apart can straddle a container recreate. The only
+authoritative clock is the timestamp on the memory, not the session/container
+boundary.
 
 **Practical rule:** prefer explicit, checkable phrasing — e.g. "earlier today,
 ~8h ago (both 2026-06-25)" — over a vague relative term. If you catch yourself