refactor: replace plant_name with per-component type keys in config

PlantFactory.create() no longer takes plant_name; sim vs real is derived
from Heater.type. StirrerFactory is wired from Stirrer.type. HeaterFactory
registry key lowercased to "hendi" to match config. Controller.plant_name
removed from both config templates.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/actor/heaterFactory.py

@@ -4,5 +4,5 @@ from components.factory import ComponentFactory, _lazy
 class HeaterFactory(ComponentFactory):
     _registry = {
         "sim":   _lazy("components.actor.heater_sim", "HeaterSim"),
-        "Hendi": _lazy("components.actor.heater_hendi", "HeaterHendi"),
+        "hendi": _lazy("components.actor.heater_hendi", "HeaterHendi"),
     }