fix(#3479): treat absent default-true mempalace keys as enabled in every prose gate (#3527)

* fix(#3479): treat absent default-true mempalace keys as enabled in every prose gate

The #2982 absent-key fix (capture_artifacts === false) was applied to only
one of the sibling gates. Five more hand-written gates in the mempalace
skill/command mirrors and the curator agent still used positive presence
('when <key> is true'), silently skipping default-enabled behavior
(mirror_kg, diary_journal) whenever the key was absent from
.planning/config.json — inverted from the registry-declared defaults.

Corrected sites, each now disabled only on an explicit false:
- skills/gsd-mempalace-capture/SKILL.md step 3 (mirror_kg)
- commands/gsd/mempalace-capture.md step 3 (mirror_kg)
- skills/gsd-mempalace-recall/SKILL.md step 3 (mirror_kg)
- commands/gsd/mempalace-recall.md step 3 (mirror_kg)
- agents/gsd-mempalace-curator.md tasks 1+2 (diary_journal, mirror_kg)

Default-false keys (mempalace.enabled, cross_project_tunnels) keep their
positive-presence gates. New #3479 regression cases in
tests/mempalace-capture-gate-default.test.cjs lock each site's absent/explicit-false
boundary and add a registry-parity guard: no gate file may positively gate
any mempalace boolean whose registry-declared default is true.

* chore(#3479): acknowledge curator size growth from the gate rewording

* chore(#3479): add changeset fragment for PR #3527

---------

Co-authored-by: sim <sim@local>

agents/gsd-mempalace-curator.md

@@ -27,9 +27,9 @@ If `mempalace.enabled !== true`, do nothing and report `MemPalace disabled — c
 
 ## Tasks (each independently best-effort)
 
-1. **Diary entry** (when `mempalace.diary_journal` is true). Write one concise per-agent diary entry summarising the phase outcome: `mempalace_diary_write(agent_name=<project>/<role>, entry=<summary>, topic="phase-ship", wing=<wing>)` (CLI: `mempalace hook run` / the diary CLI). Namespace `agent_name` by repo+role so diaries don't collide across projects. **Idempotency:** before writing, `mempalace_diary_read` (or list) for an existing entry keyed by `(wing, agent_name, topic, phase-id)`; if one exists for this phase, update it in place rather than appending a second.
+1. **Diary entry** (unless `mempalace.diary_journal !== false` — registry default is true, an absent key means enabled). Write one concise per-agent diary entry summarising the phase outcome: `mempalace_diary_write(agent_name=<project>/<role>, entry=<summary>, topic="phase-ship", wing=<wing>)` (CLI: `mempalace hook run` / the diary CLI). Namespace `agent_name` by repo+role so diaries don't collide across projects. **Idempotency:** before writing, `mempalace_diary_read` (or list) for an existing entry keyed by `(wing, agent_name, topic, phase-id)`; if one exists for this phase, update it in place rather than appending a second.
 
-2. **extract-learnings → KG mirror** (when `mempalace.mirror_kg` is true). For each decision/lesson/pattern/surprise from the phase's learnings, add a typed KG triple with provenance (`source_file`, `source_drawer_id`) and `valid_from` = the phase date. **Idempotency:** the triple `(subject, predicate, object)` is the natural key — `mempalace_kg_query` for it first and skip `mempalace_kg_add` if it already exists with the same `valid_from`, so reruns don't fork duplicate facts. When a prior decision was superseded this phase, call `mempalace_kg_invalidate` to set its `valid_to` rather than deleting it.
+2. **extract-learnings → KG mirror** (unless `mempalace.mirror_kg !== false` — registry default is true, an absent key means enabled). For each decision/lesson/pattern/surprise from the phase's learnings, add a typed KG triple with provenance (`source_file`, `source_drawer_id`) and `valid_from` = the phase date. **Idempotency:** the triple `(subject, predicate, object)` is the natural key — `mempalace_kg_query` for it first and skip `mempalace_kg_add` if it already exists with the same `valid_from`, so reruns don't fork duplicate facts. When a prior decision was superseded this phase, call `mempalace_kg_invalidate` to set its `valid_to` rather than deleting it.
 
 3. **Cross-project tunnels** (when `mempalace.cross_project_tunnels` is true). Use `mempalace_find_tunnels` to surface related wings, then `mempalace_create_tunnel(label=…)` only for connections you (or the user) can justify. **Idempotency:** check the `find_tunnels` result first and skip creation if a tunnel with that `(source-wing, target-wing, label)` already exists. Do not mass-create tunnels.