feat(ts-sdk): add reconnect() method to DbConnectionImpl

[xkelxmc]

Description of Changes

Adds a reconnect(newToken?) method to DbConnectionImpl that reopens the WebSocket on the same connection object, preserving the client cache.

Problem: Long-lived browser tabs (games, dashboards) lose their SpacetimeDB connection due to network changes, token expiration, or browser throttling. Currently the only recovery path is creating a new DbConnection, which destroys the client cache — all useTable hooks return [], causing UI flashes and loading screens.

Solution: reconnect() stores WS creation config in a private wsConfig field, silently closes the old WS (nulling handlers to prevent spurious events), then creates a new one. useTable hooks keep returning cached data while subscriptions re-establish.

connection.onDisconnect(() => {
  const freshToken = await refreshAuthToken();
  connection.reconnect(freshToken);
});

API and ABI breaking changes

None. This is a purely additive change — one new public method on DbConnectionImpl.

Expected complexity level and risk

1 — The change is small (74 lines) and self-contained. It reuses the existing WS creation pattern from the constructor. No existing behavior is modified.

Testing

• Call connection.disconnect() then connection.reconnect() — WS reconnects and onConnect fires
• useTable hooks retain cached data during reconnect
• Subscriptions re-establish after reconnect
• reconnect(newToken) uses the new token for authentication

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