Prevent stopped WebSockets from reconnecting

[JamBalaya56562]

Stopping the WebSocket transport could still open another socket: a scheduled retry survived stop(), and a pending authentication refresh called reconnect() after stopping. An old socket or refresh callback could also affect a connection started subsequently.

This change clears the retry timer, detaches and closes the socket, sets the disconnected state, and closes the transport's disconnected dialog on stop. Connection generations prevent callbacks from a previous connection from reconnecting or changing current state. Explicit restart retains subscriptions, while normal five-second retries and authentication refresh remain supported.

Validation

• Before the fix: 7 of the initial 13 tests failed, reproducing connections after stop, refresh-driven replacement of a restarted socket, and stale state updates; 6 normal-path tests passed.
• After the fix: all initial 13 passed. Added three further cases for failed refresh after restart and the normal timed retry following a failed 4401 refresh, for 16 lifecycle tests in total.
• bun install --frozen-lockfile and Prettier check passed.
• bun run test:ci: 36 files / 380 tests passed.
• bun run gen:font and bun run ng -- build ngclient --configuration production passed.

Tests use a fake WebSocket, controlled RxJS Subjects, fake timers, and a dialog fake. No real WebSocket server or manual GUI reproduction was used. Shared authentication behavior, API types, dependencies, and lockfiles are unchanged.

Part of #273. Related to #283; this does not claim to resolve every reconnection issue.