feat: add InvenTree Cloudron package (Business-Apps) [#658]

Official-image wrapper of inventree/inventree 1.5.2 (digest-pinned).
allauth OIDC provider JSON built from the platform env; invoke update
on boot; RQ worker behind the web-port gate; admin seeded with a
generated password. grind-stack: lowercase image names. 19th package.
Verified: health 200, SSO route 302s to issuer, migrations clean.

Detail: https://projects.knownelement.com/issues/658#note-5086

Package-Workspace/Business-Apps/InvenTree/CHANGELOG.md

@@ -0,0 +1,12 @@
+# Changelog — InvenTree Cloudron Package
+
+## 1.0.0 — 2026-09-06
+
+- Initial package: InvenTree 1.5.2 (official-image wrapper, digest
+  pinned sha256:2df695b3…)
+- postgresql + redis + localstorage addons; gunicorn on :8000
+- INVENTREE_* env mapped from the platform; data dir pinned to
+  /app/data (media/static/config + persisted secret key)
+- OIDC provider JSON built from CLOUDRON_OIDC_* (allauth
+  openid_connect, PKCE); local admin seeded with generated password
+- `invoke update` on boot; RQ worker backgrounded behind web-port gate