feat: impl docs (#4)

The entire public api is covered with documentation in two languages - Russian and English.

the library now supports the latest three versions of python - 3.12, 3.13 and 3.14

minor design changes: now, when a Boolean flag is entered, its value is an empty string, not None.

tests have been adapted to the supported versions of python, readmi has been redesigned in two languages, German is no longer available.

docs/code_snippets/testing/di_handler_unittest.py

@@ -0,0 +1,42 @@
+import io
+from contextlib import redirect_stdout
+
+from argenta.command import InputCommand
+from dishka import Provider, make_container, Scope
+
+from argenta import Router, Response
+from argenta.di.integration import setup_dishka, FromDishka
+
+
+class Service:
+    def hello(self) -> str:
+        return "world"
+        
+def get_service() -> Service:
+    return Service()
+        
+
+router = Router(title="DI")
+
+@router.command("HELLO")
+def hello(response: Response, service: FromDishka[Service]) -> None:
+    print(f"hello {service.hello()}")
+    
+    
+class _FakeApp:
+    # Minimal stub for setup_dishka; app object is not used in unit tests
+    registered_routers = [router]
+
+
+def test_hello_uses_service():
+    provider = Provider(scope=Scope.APP)
+    provider.provide(get_service)
+    
+    container = make_container(provider)
+    setup_dishka(app=_FakeApp(), container=container, auto_inject=True)
+
+    # Call handler
+    with redirect_stdout(io.StringIO()) as stdout:
+        router.finds_appropriate_handler(InputCommand.parse('HELLO'))
+
+    assert "hello world" in stdout.getvalue()