feat(djinit/templates/components): expose configurable app_config_name placeholder in AppConfig template

Allows the generated AppConfig class to use a custom name derived from `app_config_name`, supporting optional `app_module` specification.

New Features
- Replace `app_name|title` placeholder with `app_config_name` for flexible config naming.
- Add conditional block that sets `name` to `app_module` when provided, otherwise falls back to `app_name`.

Enhancements
- Maintain backward compatibility by defaulting to the original `app_name` behavior.
- Improve template flexibility for future naming conventions.

Bug Fixes
- None.

djinit/templates/components/apps.py-tpl

@@ -1,6 +1,12 @@
 from django.apps import AppConfig
 
 
-class [[ app_name|title ]]Config(AppConfig):
+
+class [[ app_config_name ]]Config(AppConfig):
     default_auto_field = 'django.db.models.BigAutoField'
+# @IF app_module
+    name = '[[ app_module ]]'
+# @ENDIF
+# @IF not app_module
     name = '[[ app_name ]]'
+# @ENDIF