Feature: mouse interactions in the settings editor #39

Goal

Make the interactive settings editor usable with the same mouse capture already provided by the dashboard.

Scope

• Hit-test visible settings rows using the rendered popup and content scroll offset.
• Move the selected field with pointer clicks and wheel events without changing keyboard behavior.
• Apply the existing Enter/Space behavior from a left click: toggle booleans, cycle enum values, and enter edit mode for numeric/text fields.
• Add mouse targets for review-save, confirm-save, cancel, and close actions in the settings footer.
• Keep clicks outside the popup, section headers, and inactive overlays from changing configuration.
• Preserve narrow-terminal layout and ensure unsaved changes remain explicit before writing.

Acceptance criteria

• Clicking a visible setting selects it and performs the same action as the equivalent keyboard command.
• Wheel movement navigates settings and keeps the selected row visible.
• Save and cancel flows can be completed with mouse clicks, including confirmation and discard paths.
• Pointer actions never mutate settings when outside an actionable row or footer control.
• Keyboard-only behavior remains unchanged and deterministic tests cover row, scroll, footer, and narrow-layout boundaries.