release: v4.0.0 — ecosystem integration (marketplace, interop, skill API)

- Add marketplace metadata to both plugin manifests (author, license, category, tags)
- Declare lossless-claw complementary positioning via interop field
- Expose mc:recall as programmatic service (api.exposeService)
- Fix CJK hashtag regex to support Unicode property escapes
- Create MARKETPLACE.md for marketplace listing
- Update README with marketplace install, interop docs, and API docs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

MARKETPLACE.md

@@ -0,0 +1,49 @@
+# Memory Continuity — Marketplace Listing
+
+## What it does
+
+Memory Continuity is a **zero-dependency lifecycle plugin** that preserves your working state across session resets, compaction, and gateway restarts. It answers one question:
+
+> What were we doing, where did we stop, and what should happen next?
+
+## Key features
+
+- **Automatic state checkpoint** — saves working state at session end, before /new, and before compaction
+- **Session logging** — daily markdown logs of all sessions with topic, message count, and token estimates
+- **Layered summaries** — daily summaries roll up into weekly summaries
+- **Tag extraction** — #tag patterns auto-indexed in memory/tags.md
+- **Relevance injection** — injects related history at session start based on keyword matching
+- **Memory decay** — old archives move to cold storage after configurable days
+- **CJK-aware** — proper token estimation for Chinese/Japanese/Korean text
+- **Search & recall** — /mc search and /mc recall for cross-memory search
+- **Programmatic API** — other plugins can call mc:recall service directly
+
+## Why this plugin?
+
+| Feature | Memory Continuity | Other memory plugins |
+|---------|------------------|---------------------|
+| Dependencies | Zero | SQLite, Chroma, APIs |
+| Data format | Plain markdown | Proprietary DB |
+| Backup strategy | cp / scp | DB export |
+| Migration | Copy files | Re-index |
+| contextEngine slot | Not used | Often required |
+| Works with lossless-claw | Yes | Varies |
+
+## Works with lossless-claw
+
+MC intentionally does NOT use the contextEngine slot. It runs via lifecycle hooks only. This means you can install both:
+
+- **lossless-claw** — lossless context compression (contextEngine slot)
+- **memory-continuity** — working-state recovery (hooks only)
+
+They serve complementary purposes and never conflict.
+
+## Install
+
+```
+openclaw plugins install https://github.com/dtzp555-max/memory-continuity
+```
+
+## Configuration
+
+All settings are optional with sensible defaults. See `openclaw plugins inspect memory-continuity` for the full config schema.