add rpc addon and fix 19.0 compatibility issues

- add missing rpc addon (auto_install, required by server_wide_modules)
- add __init__.py -> init.py symlink for odoo package importability
- re-export image_process from odoo.tools (needed by web_editor)
- add backward-compatible slug/unslug functions in http_routing

🤖 assisted by claude

odoo-bringout-oca-ocb-http_routing/http_routing/models/ir_http.py

@@ -628,3 +628,14 @@ class IrHttp(models.AbstractModel):
         except werkzeug.exceptions.NotFound:
             new_url = path
         return new_url or path, endpoint and endpoint[0]
+
+
+# Backward-compatible module-level functions that delegate to IrHttp class methods.
+# In Odoo 19.0 these were moved to IrHttp._slug/_unslug, but many addons
+# still import them as standalone functions.
+def slug(value):
+    return IrHttp._slug(value)
+
+
+def unslug(value):
+    return IrHttp._unslug(value)