fix(connection): show ConnectionPage on startup and all non-ready Klipper states

[gmmcosta15]

Description

- [x] Bug fix

ConnectionPage was not shown during startup or while Klipper was initializing, causing the main UI tabs to be exposed before the printer was ready.

• Removed _AUTO_SHOW_STATES guard from ConnectionPage._set_state - the page now auto-shows for every non-KLIPPER_READY state when it is hidden and conn_toggle is True.
• Added self.conn_window.show() at the end of MainWindow.init so the page is visible from the moment the window opens, before the first WebSocket state signal arrives.
• Updated TestVisibility in test_connection_page.py: replaced test_auto_show_states_call_show with test_all_non_ready_states_auto_show (iterates all ConnectionState members except KLIPPER_READY) and removed test_non_auto_show_does_not_show (behavior is now inverted by design).

Motivation

On boot the app went through CONNECTING → MOONRAKER_CONNECTED → KLIPPER_STARTUP without showing ConnectionPage, so the user could interact with print/control/filament tabs while the printer was still initialising. The fix makes the page visible for the entire startup sequence and hides it only once Klipper reports ready.

Tests

All 1193 tests pass (make test-fast). TestVisibility now covers all eight non-ready ConnectionState values.