fix: Add defensive type checking to lifespan and admin seed functions

Discovered during Session 38: the redis_client.py type hint import fix
revealed a deeper issue in the data model loading code. When iterating
through layer JSON files to seed data, the code assumed all array items
were dictionaries, but some items (especially in eva-model.json) are
other types (strings, objects).

Added type checks:
- api/server.py lifespan: Filter out non-dict items before calling setdefault()
- api/routers/admin.py seed endpoint: Same type safety improvements
- Both now check isinstance(o, dict) before treating items as dicts

This fixes:
- tests/test_admin.py::test_T32_seed_loads_all_layers (was failing)
- tests/test_admin.py::test_T36_row_version_increments_on_reseed (was failing)
- All 9 admin tests now passing

Root cause: When JSON has nested arrays or mixed content, dict.values()
iteration would find the first list and assume it's all dicts. Now we
explicitly filter to dicts-only to be defensive.

Author: MarcoPolo483

api/routers/admin.py

@@ -157,7 +157,11 @@ async def seed(
                     objects = v
                     break
 
+        # Ensure objects is a list and filter to dicts only
+        if not isinstance(objects, list):
+            objects = []
         # Normalise: ensure every object has an 'id' field
+        objects = [o for o in objects if isinstance(o, dict)]
         for obj in objects:
             if "id" not in obj and "key" in obj:
                 obj["id"] = obj["key"]

api/server.py

@@ -144,7 +144,11 @@ async def lifespan(app: FastAPI):
                         if isinstance(v, list):
                             objects = v
                             break
+            # Ensure objects is a list and filter to dicts only
+            if not isinstance(objects, list):
+                objects = []
             # normalise id + stamp source_file
+            objects = [o for o in objects if isinstance(o, dict)]
             for obj in objects:
                 if "id" not in obj and "key" in obj:
                     obj["id"] = obj["key"]