fix(deploy): vendor OpenEduCat Community 19.0 under backend/

Database dumps list 12 openeducat_* modules as installed (openeducat_core,
openeducat_admission, openeducat_assignment, openeducat_attendance,
openeducat_activity, openeducat_classroom, openeducat_exam, openeducat_facility,
openeducat_fees, openeducat_library, openeducat_parent, openeducat_timetable),
but the `backend/openeducat_erp-19.0/` folder was previously in .gitignore.
When a teammate restored the dump on the VPS Odoo failed with "module not
found" on every openeducat_* row in ir_module_module.

- Remove `backend/openeducat_erp-19.0/` from .gitignore and vendor the full
  LGPL-3 OpenEduCat Community 19.0 tree (14 modules: 12 core + theme + erp
  meta-module). `odoo.conf` and `odoo-docker.conf` already reference this
  path in `addons_path`, so restores now succeed on a fresh VPS with no
  extra bootstrap step.
- Strip the nested .git metadata that came with the upstream download so
  the tree is vendored flat (not as a submodule pointer).

Made-with: Cursor

.gitignore

@@ -88,9 +88,13 @@ addons_enterprise/
 addons_extra/
 new_project/enterprise-17/
 
-# Third-party modules (downloaded separately)
+# Third-party modules
+# OpenEduCat Community (LGPL-3) is vendored under `backend/openeducat_erp-19.0/`
+# and must be tracked — `addons_path` in odoo.conf / odoo-docker.conf relies on
+# it, and database dumps mark 12 openeducat_* modules as installed. Excluding
+# this folder previously caused restores on the VPS to fail with "module not
+# found" errors.
 new_project/openeducat_erp-19.0/
-backend/openeducat_erp-19.0/
 new_project/openeducat_erp-19.0.zip
 new_project/openeducate_enterprise-17.zip
 new_project/encoach_frontend_new_v1-main.zip