Make startup crash-proof against corrupt/empty state

- database.py: catch JSONDecodeError when loading snapshot from DB
- server.py: wrap load_simulation() in try/except — any error starts fresh

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

src/soci/api/server.py

@@ -275,8 +275,13 @@ async def lifespan(app: FastAPI):
     data_dir = Path(os.environ.get("SOCI_DATA_DIR", "data"))
     await load_state_from_github(data_dir)
 
-    # Try to resume
-    sim = await load_simulation(db, llm)
+    # Try to resume — any failure falls back to a fresh simulation
+    sim = None
+    try:
+        sim = await load_simulation(db, llm)
+    except Exception as e:
+        logger.warning(f"Failed to load saved simulation, starting fresh: {e}")
+
     if sim is None:
         # Create new
         config_dir = Path(__file__).parents[3] / "config"

src/soci/persistence/database.py

@@ -98,7 +98,10 @@ class Database:
             )
         row = await cursor.fetchone()
         if row:
-            return json.loads(row[0])
+            try:
+                return json.loads(row[0])
+            except (json.JSONDecodeError, ValueError) as e:
+                logger.warning(f"Corrupt snapshot in DB, ignoring: {e}")
         return None
 
     async def list_snapshots(self) -> list[dict]: