Use a small Material triangle for settings expander disclosure icon

[gbeane]

The collapsible "More info" sections in the settings dialogs used QToolButton.setArrowType(), which draws the Qt style's arrow primitive — chunky and not easily sized.

This swaps it for a small Material disclosure triangle in the shared CollapsibleSection widget:

• arrow_right when collapsed, arrow_drop_down when expanded, at 16px.
• Uses the already-bundled qt_material_icons, which renders in the palette text color, so it follows the application theme (matching how sibling dialogs already use MaterialIcon).
• The native arrow is removed (arrowType is now NoArrow); the toggle/resize behavior is otherwise unchanged.

Because it's the shared widget, every settings "More info" expander updates consistently.

Tests

• Added test_collapsible_section_toggles_disclosure_icon: verifies the icon swaps on expand and reverts on collapse, and that no native arrow is drawn.
• Settings-dialog tests pass; lint and format clean.

It's a visual tweak, so a quick look in the GUI confirms the appearance; the toggle behavior is covered by the test.

[Copilot]

Pull request overview

Updates the shared settings-dialog CollapsibleSection widget to use a small Material disclosure triangle (instead of Qt’s native arrow primitive) so expander indicators are consistently themed and appropriately sized across dialogs.

Changes:

• Replace QToolButton.setArrowType() usage with qt_material_icons.MaterialIcon for collapsed/expanded disclosure indicators.
• Set the disclosure icon size to 16px and swap icons on toggle.
• Add a UI test ensuring the icon changes on expand/collapse and that no native arrow is used.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/jabs/ui/settings_dialog/collapsible_section.py	Switches disclosure indicator from native arrow to Material icons and updates toggle behavior to swap icons.
tests/ui/test_settings_dialog.py	Adds a regression test covering disclosure icon swapping and verifying NoArrow is used.

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