Extract shared factory dispatch into ComponentFactory base class

All four name-dispatch factories repeated the same if/elif lazy-import
pattern. Replace with a ComponentFactory base class holding a callable
registry and a _lazy() helper for the common import-and-construct case.
PlantFactory is an orchestrator, not a dispatcher, and is left as-is.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Tqxrk8uj4M3w3d3eXm3xK8

components/factory.py

@@ -0,0 +1,19 @@
+import importlib
+
+
+def _lazy(module, classname):
+    """Return a builder that lazily imports module.classname on first call."""
+    def build(*args, **kwargs):
+        return getattr(importlib.import_module(module), classname)(*args, **kwargs)
+    return build
+
+
+class ComponentFactory:
+    _registry = {}
+
+    @classmethod
+    def create(cls, name, *args, **kwargs):
+        for key, builder in cls._registry.items():
+            if key in name:
+                return builder(*args, **kwargs)
+        raise ValueError(f"{cls.__name__}: unknown name {name!r}")