refactor(sonar): clean up issues reported on PR 209

- remove locals left unused after the dead-store cleanup (cpp:S1481, cpp:S1854)
- unnamed unused parameter (cpp:S1172)
- single-use declarations moved into if init-statements (cpp:S6004)
- auto for casted initialisers (cpp:S5827)
- const references and pointers where nothing is modified (cpp:S5350)
- rename structured bindings shadowed by inner declarations (cpp:S1117)

scripting/PyInt.cpp

@@ -376,7 +376,7 @@ void python_taskqueue::exit()
 	// reclaim cached python objects while the interpreter is still alive,
 	// so no Py_DECREF lands on a finalized interpreter during later teardown
 	acquire_lock();
-	for (auto &[renderername, rendererobject] : m_renderers)
+	for (auto const &[renderername, rendererobject] : m_renderers)
 	{
 		Py_XDECREF(rendererobject);
 	}