feat: add shadow-only joint EV and home-battery planning

Author: arturonaredo

README.md

@@ -1,5 +1,8 @@
 # Predbat
 
+> Experimental [joint EV/home-battery planning](docs/joint-site-planning.md)
+> is opt-in and shadow-only. It never replaces the executable native plan.
+
 ![image](https://github.com/springfall2008/batpred/actions/workflows/code-quality.yml/badge.svg)
 ![image](https://github.com/springfall2008/batpred/actions/workflows/publish-docs.yml/badge.svg)
 ![image](https://github.com/springfall2008/batpred/actions/workflows/pages/pages-build-deployment/badge.svg)

apps/predbat/config.py

@@ -2597,6 +2597,7 @@
 
 # Apps.yaml validation schema
 APPS_SCHEMA = {
+    "joint_site": {"type": "dict"},
     "currency_symbols": {"type": "string|string_list"},
     "db_enable": {"type": "boolean"},
     "db_days": {"type": "integer"},

apps/predbat/ha.py

@@ -853,7 +853,9 @@ def update_state_item(self, item, entity_id, nodb=False):
         last_changed = item.get("last_changed", item.get("last_updated", None))
         if "state" in item:
             state = item["state"]
-            self.state_data[entity_id] = {"state": state, "attributes": attributes, "last_changed": last_changed}
+            # Preserve observation freshness separately from a state transition.
+            # An unchanged SOC may have a fresh device timestamp/attribute update.
+            self.state_data[entity_id] = {"state": state, "attributes": attributes, "last_changed": last_changed, "last_updated": item.get("last_updated", last_changed)}
             if not nodb and self.db_enable and ((self.db_mirror_ha and (entity_id in self.db_mirror_list)) or self.db_primary):
                 # Instead of appending to a local mirror_updates list, call the database manager to schedule the update
                 if last_changed: