refactor(minijinja): migrate callers to plugins.minijinja and remove contrib path

- Migrate every internal call site (tests, doc examples, the lazy
  import inside `litestar.plugins.flash`) to
  `from litestar.plugins.minijinja import ...`. The flash.py change
  preserves the public/private split: it still imports both
  `MiniJinjaTemplateEngine` and the module-level `_transform_state`
  helper.
- Delete `litestar/contrib/minijinja.py`. The contrib path is gone on
  main; the v2 follow-up PR adds a deprecation shim at the contrib
  location covering both public symbols and `_transform_state`, so 2.x
  users (whose flash.py still imports from contrib) get a
  `DeprecationWarning` window with a real migration target on the
  version they are already running.
- Salvage the contrib functional tests into
  `tests/unit/test_plugins/test_minijinja.py` (99% line coverage on
  the new module) and delete `tests/unit/test_contrib/test_minijinja.py`.
- Add `docs/reference/plugins/minijinja.rst`; update the plugins
  reference toctree.

Co-authored-by: xronocode <myevdokimov@gmail.com>

Author: cofin

docs/examples/plugins/flash_messages/minijinja.py

@@ -1,5 +1,5 @@
 from litestar import Litestar
-from litestar.contrib.minijinja import MiniJinjaTemplateEngine
+from litestar.plugins.minijinja import MiniJinjaTemplateEngine
 from litestar.middleware.session.server_side import ServerSideSessionConfig
 from litestar.plugins.flash import FlashConfig, FlashPlugin
 from litestar.template.config import TemplateConfig

docs/examples/templating/engine_instance_minijinja.py

@@ -1,4 +1,4 @@
-from litestar.contrib.minijinja import MiniJinjaTemplateEngine
+from litestar.plugins.minijinja import MiniJinjaTemplateEngine
 from litestar.template.config import TemplateConfig
 
 template_config = TemplateConfig(engine=MiniJinjaTemplateEngine, directory="templates")

docs/examples/templating/returning_templates_minijinja.py

@@ -3,7 +3,7 @@
 from pathlib import Path
 
 from litestar import Litestar, get
-from litestar.contrib.minijinja import MiniJinjaTemplateEngine
+from litestar.plugins.minijinja import MiniJinjaTemplateEngine
 from litestar.response import Template
 from litestar.template.config import TemplateConfig
 

docs/examples/templating/template_engine_minijinja.py

@@ -1,7 +1,7 @@
 from pathlib import Path
 
 from litestar import Litestar
-from litestar.contrib.minijinja import MiniJinjaTemplateEngine
+from litestar.plugins.minijinja import MiniJinjaTemplateEngine
 from litestar.template.config import TemplateConfig
 
 app = Litestar(

docs/examples/templating/template_functions_minijinja.py

@@ -1,7 +1,7 @@
 from pathlib import Path
 
 from litestar import Litestar, get
-from litestar.contrib.minijinja import MiniJinjaTemplateEngine, StateProtocol
+from litestar.plugins.minijinja import MiniJinjaTemplateEngine, StateProtocol
 from litestar.response import Template
 from litestar.template.config import TemplateConfig
 

docs/reference/plugins/index.rst

@@ -12,6 +12,7 @@ plugins
     attrs
     flash_messages
     htmx
+    minijinja
     opentelemetry
     problem_details
     prometheus

docs/reference/plugins/minijinja.rst

@@ -0,0 +1,6 @@
+=========
+minijinja
+=========
+
+.. automodule:: litestar.plugins.minijinja
+    :members:

litestar/contrib/minijinja.py

@@ -59,7 +59,7 @@ def on_app_init(self, app_config: AppConfig) -> AppConfig:
             raise litestar.exceptions.ImproperlyConfiguredException("Flash messages require a session middleware.")
         template_callable: Callable[[Any], Any] = get_flashes
         with suppress(MissingDependencyException):
-            from litestar.contrib.minijinja import MiniJinjaTemplateEngine, _transform_state
+            from litestar.plugins.minijinja import MiniJinjaTemplateEngine, _transform_state
 
             if isinstance(self.config.template_config.engine_instance, MiniJinjaTemplateEngine):
                 template_callable = _transform_state(get_flashes)