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/MetaFeederArxiv/rationale.md

@@ -0,0 +1,33 @@
+# MetaFeeder · arXiv — Rationale
+
+## What deviation / exception is being requested
+
+`metafeederarxiv-feeder` runs `user: 0:0`.
+
+## Why it is necessary
+
+Carried over unchanged from the listing this app was split out of (MetaFeeder · Papers), so the
+feeder behaves exactly as it did there. The MetaFeeder images write their state and
+redb cache as the container user and some reach MetaCore's root-owned tree; a uid-1000
+process is refused.
+
+## Security mitigations in place
+
+- Public ingress terminates at the AppShield sidecar (`ghcr.io/yundera/appshield:2.0.9`),
+  which gates every path behind the PCS's Authelia SSO over OIDC. The feeder carries no
+  Caddy labels and publishes no host port, so it is reachable only from the `pcs` Docker
+  network.
+- The container mounts **no user directories** — not `/DATA/Documents`, `/DATA/Downloads`,
+  `/DATA/Media` or `/DATA/Gallery`. Its only bind is its own state under
+  `/DATA/AppData/metafeederarxiv/`, declared in `x-compose-app.folders` and owned `$PUID:$PGID`.
+- `cpu_shares` set on every service; image tags pinned; no `:latest`.
+
+## Alternatives considered and rejected
+
+- **Run as `$PUID:$PGID`.** Not validated for this image; switching the runtime user in
+  the same change as the split would mix a behaviour change into a packaging change.
+
+## Data protection
+
+The feeder holds no user media. Its entire state lives under `/DATA/AppData/metafeederarxiv/`, which
+is the unit Maison archives on uninstall and restores from backup.