In Zabbix 8.0 dashboard edit mode, widget configuration opens in a floating dialog positioned over the dashboard. The edited widget is highlighted and changes are already previewed in the widget before "Apply", but the dialog stays on top of the dashboard grid. It often covers the edited widget itself or the widgets next to it, so users have to drag the dialog aside manually to see the preview. The dashboard layout doesn't adapt to the dialog, and the dialog can also end up hidden under other UI elements (see ZBX-27443).

Proposal
Open the widget configuration form in a panel docked on the right side of the screen instead of the floating dialog. When the panel opens, the dashboard area shrinks to the remaining width and widgets reflow responsively, so the edited widget and its live preview always stay visible without moving anything manually.

Acceptance criteria

1. The configuration panel opens docked on the right side and doesn't cover the dashboard grid.
2. The dashboard grid resizes to the remaining width; widgets stay readable and keep their relative layout.
3. The edited widget stays highlighted and is kept in view (scrolled into view if needed).
4. The existing live preview keeps working in the panel; changes persist only after "Apply"; "Cancel" or Esc restores the previous state, as today.
5. The panel width can be adjusted, and the panel can be closed with the close button or Esc.
6. On narrow screens, the panel falls back to a full-width overlay.
7. Keyboard and screen reader access: focus moves into the panel on open and returns to the widget on close; the panel has an accessible name.
8. Works with all built-in and module widgets, both when editing an existing widget and when adding a new one.