fix(tao): match AWT trackpad scrolling on macOS and surface Pan events (#656) [2.6] - #661

Cherry-pick of #656 onto nucleus-2.6 (#652, #653, #654).

What it ports

• Horizontal trackpad scrolling matches AWT (no extra X flip).
• Precise deltas are logical points, not physical pixels (no display-scale 2× on Retina).
• Trackpad gestures reach Compose as PanStart / PanMove / PanEnd; wheel notches stay Scroll.
• One TaoSceneScrollRouter for the window host and macOS NSPanel popups.
• Native views get the whole pan (begin/end included). Trackpad Lab tab in nucleus-demo.

2.6 merge notes

• Tao patch is 0008 here: 2.6 already used 0007 for the Linux outer-geometry placeholder.
• Kept 2.6-only pieces that overlapped: syncSceneSize (nativePopupLayers: popups position against the window, not the screen (flip/clip uses a window-rooted work area) #569), NativePopupLayers / MacPopupPictureCull battery cases, the Popups demo tab, the “Tao is the only backend” CLAUDE.md paragraph.

Verify

• :decorated-window-tao:compileKotlin / compileTestKotlin / native macOS rebuild
• :examples:nucleus-demo:compileKotlin
• unit tests: TaoTrackpadPanRouterTest, TaoSceneTrackpadPanTest, TaoScrollWireDriftTest, TaoSceneTestBatteryDriftTest, MacOsWheelDeltaTest, TaoWindowScrollTest, TaoSceneScrollTest
• ktlint on the touched source sets