security: harden JWT auth with session binding, CSP headers, and sessionStorage

- Reduce access_token_ttl from 900s to 300s (5 min) to shrink XSS exploit window
- Add session_id claim to JWT tokens tied to browser session (X-Session-Id header)
- Flask middleware validates session_id matches header on every request
- CSP headers: default-src/script-src 'self', no unsafe-inline/eval, frame-ancestors none
- X-Content-Type-Options: nosniff on all responses
- Move refresh token from localStorage to sessionStorage (tab-scoped, cleared on close)
- Timing-safe password verification (dummy Argon2id for unknown users)
- WebSocket auth also validates session_id header
- Add 5 session_id tests and 3 CSP header tests

daemon/handlers/auth.py

@@ -195,6 +195,31 @@ def auth_refresh(_request: Any, body: Any) -> dict[str, Any]:
         },
         "permissions": permissions,
     }
+    if payload is None:
+        raise ValueError("Invalid or expired refresh token")
+
+    username = payload["sub"]
+    user = get_user(username)
+    if user is None:
+        raise ValueError("User not found")
+
+    jti = payload.get("jti")
+    if jti:
+        blacklist_token(jti, token_type="refresh")
+    if username:
+        _clear_refresh_token_after_rotation(username)
+    permissions = user["permissions"]
+    tokens = generate_tokens(username, permissions)
+
+    return {
+        "tokens": tokens,
+        "access_ttl": get_access_ttl(),
+        "user": {
+            "id": user["id"],
+            "username": user["username"],
+        },
+        "permissions": permissions,
+    }
 
 
 @registry.register(GET_AUTH_SESSION)