fix(server): replace CORS wildcard fallback with closed localhost list (#283)

server/app.py defaulted to allow_origins=["*"] combined with
allow_credentials=True when cors_origins was not passed. That
combination is invalid per the CORS spec — browsers reject it — and
when used loosely it signals that any cross-origin request with
credentials is allowed, exposing session cookies and auth headers.

The reference config at configs/openjarvis/config.toml binds to
0.0.0.0 without setting cors_origins, so this fallback fired in every
default deployment.

Default to a closed list (Vite dev origin + Tauri webview) instead of
the wildcard. Users who actually need a custom origin already pass it
via cors_origins.

Closes #222

src/openjarvis/server/app.py

@@ -181,7 +181,15 @@ def create_app(
 
     from fastapi.middleware.cors import CORSMiddleware
 
-    _origins = cors_origins if cors_origins is not None else ["*"]
+    _origins = (
+        cors_origins
+        if cors_origins is not None
+        else [
+            "http://localhost:5173",
+            "http://127.0.0.1:5173",
+            "tauri://localhost",
+        ]
+    )
     app.add_middleware(
         CORSMiddleware,
         allow_origins=_origins,