* Dock: add touch support for Tab/Tab bar interactions (scroll, drag/drop)
Details below:
1. **Finger-based tab drag-and-drop via long press** (tab.rs, android.rs, ios.rs):
- On touch devices, tab dragging now requires a long press before moving,
distinguishing it from scroll gestures.
- Added internal drag-and-drop support for Android and iOS backends,
synthesizing Drag/Drop/DragEnd events from touch move/up, matching the
existing Linux X11/Wayland approach.
2. **Finger-based drag-scrolling through the tab bar** (tab.rs, tab_bar.rs):
- A finger down + move (without long press) on a tab now scrolls the tab bar
horizontally instead of initiating a tab drag.
- Includes flick-to-scroll with velocity and decay for natural momentum.
- Touch tab selection is deferred to finger-up and only fires on a clean tap
(no long press, no scroll gesture), so scrolling/dragging doesn't
accidentally select tabs.
3. **Horizontal scroll input for tab bar** (scroll_bar.rs):
- When `use_vertical_finger_scroll` is enabled on a horizontal scroll bar,
both horizontal (trackpad) and vertical (mouse wheel) scroll inputs are
accepted, so trackpad users can scroll the tab list in either direction.
* fix drag/drop on macOS by using internal drag logic.
Fix ghost tab on dock to be much cleaner in terms of behavior
* Cleanup dock tab drag&drop behavior
Make platforms consistent. Switch macOS to internal drag item tracking
instead of OS-native (just for the dock for now).
Ensure ghost tab that gets drawn is consistently hidden (instantly)
upon being dropped in an invalid target zone.
Details below:
1. **Finger-based tab drag-and-drop via long press** (tab.rs, android.rs, ios.rs):
- On touch devices, tab dragging now requires a long press before moving,
distinguishing it from scroll gestures.
- Added internal drag-and-drop support for Android and iOS backends,
synthesizing Drag/Drop/DragEnd events from touch move/up, matching the
existing Linux X11/Wayland approach.
2. **Finger-based drag-scrolling through the tab bar** (tab.rs, tab_bar.rs):
- A finger down + move (without long press) on a tab now scrolls the tab bar
horizontally instead of initiating a tab drag.
- Includes flick-to-scroll with velocity and decay for natural momentum.
- Touch tab selection is deferred to finger-up and only fires on a clean tap
(no long press, no scroll gesture), so scrolling/dragging doesn't
accidentally select tabs.
3. **Horizontal scroll input for tab bar** (scroll_bar.rs):
- When `use_vertical_finger_scroll` is enabled on a horizontal scroll bar,
both horizontal (trackpad) and vertical (mouse wheel) scroll inputs are
accepted, so trackpad users can scroll the tab list in either direction.
