Import the MetaMesh app family from Worph/AppStore

23 apps (MetaCore, the library/network/client tiers and 13 MetaFeeder*)
move out of the general-purpose Worph/AppStore into their own store so the
MetaMesh family releases on its own cadence.

- asset URLs repointed to cdn.jsdelivr.net/gh/Worph/MetaAppStore@main
- store scaffolding added (category/recommend/featured lists, licence,
  contributing, gitattributes)
- psd-source/meta-icons-v2 icon generator follows the apps

MetaMCP stays in Worph/AppStore: it is third-party metatool-ai software,
not part of MetaMesh.

Apps/MetaSort/rationale.md

@@ -0,0 +1,48 @@
+# MetaSort — Rationale
+
+## What deviation / exception is being requested
+
+1. `metasort-app` runs `user: 0:0`.
+2. It mounts the Docker socket, `/var/run/docker.sock`, read-only.
+3. It mounts `/DATA/AppData/metacore/meta-core` — another app's AppData directory.
+
+## Why it is necessary
+
+1. MetaSort writes its service registration into `/meta-core/services/`, a directory
+   created and owned by MetaCore's root-running container, and runs nginx internally.
+2. MetaSort's enrichment plugins are **containers**. It lists, starts and stops them on the
+   `pcs` network (`CONTAINER_NETWORK=pcs`), and receives their results on
+   `CONTAINER_CALLBACK_URL`. Driving container lifecycle requires the Docker API.
+3. `/meta-core` is the shared leader-election and service-discovery directory. MetaCore is
+   a hard prerequisite of this app.
+
+## Security mitigations in place
+
+- **The socket is mounted `:ro`.** That limits the *bind*, not the API — a read-only socket
+  bind still permits write calls — so the meaningful control is the perimeter: the
+  container carries no Caddy labels, publishes no host port, and is reachable only from
+  the `pcs` network.
+- Public ingress terminates at the AppShield sidecar (`ghcr.io/yundera/appshield:2.0.9`)
+  behind Authelia SSO; only `/health` is exempt.
+- MetaSort's own state is confined to `/DATA/AppData/metasort/cache/`, declared in
+  `x-compose-app.folders`.
+- `cpu_shares` set on both services; image tags pinned.
+
+## Alternatives considered and rejected
+
+- **A Docker-socket proxy (e.g. tecnativa/docker-socket-proxy) allowing only the endpoints
+  MetaSort uses.** This is the right long-term shape and is the intended follow-up. It is
+  not shipped here because plugin lifecycle needs `containers`, `images`, `exec` and
+  `networks` write access, which is most of the API surface anyway; the proxy would narrow
+  the blast radius without eliminating it.
+- **Run plugins as sibling compose services instead of on-demand containers.** Plugins are
+  installed and removed by the user at runtime; a static compose file cannot express that.
+- **Run as `$PUID:$PGID`.** Fails writing into MetaCore's root-owned
+  `/meta-core/services/`.
+
+## Data protection
+
+MetaSort holds no user media — it reads metadata through MetaCore and caches derived data
+under `/DATA/AppData/metasort/cache/`, which Maison archives and restores. Its access to the
+user's files is indirect, through MetaCore's WebDAV endpoint, and is bounded by what
+MetaCore itself exposes (read-only mounts of `/DATA/Downloads` and `/DATA/Media`).