fix: WS reconnection deadlock, remove redundant try/except, fix docs

- websocket.js: schedule reconnect backoff when token refresh fails,
  otherwise WebSocket stays dead after 3+ disconnects with failed refresh
- daemon/handlers/auth.py: remove two redundant try/except ValueError: raise
  blocks in webauthn register/authenticate finish handlers
- docs/api.md: mark permissions as optional in Create User endpoint

docs/api.md

@@ -204,7 +204,7 @@ Create a new user with password and per-subsystem permissions.
 |---|---|---|---|
 | `username` | `string` | Yes | Username |
 | `password` | `string` | Yes | Plain-text password |
-| `permissions` | `object` | Yes | Per-subsystem permissions (`{ subsystem: "read" \| "rw" }`) |
+| `permissions` | `object` | No | Per-subsystem permissions (`{ subsystem: "read" \| "rw" }`) |
 
 **Response:** `data` is `null` on success.