Drop the 32pt drag-overlay clearance above the sidebar tab strip to a
12pt inset - just enough to clear the window's 12pt drag overlay so
every tab pixel stays clickable - and shrink the header from 98pt to
78pt. Follow-up to #103438 per maintainer feedback.
Each inline link opens in its own tab (exact-URL dedupe); sidebar
target=_blank links open new tabs. Tab strip on top with click to
activate, close buttons, middle-click close, pointer-drag reorder, and
a per-tab context menu (Open in Default Browser, Copy Link, Reload,
Close Tab, Close Other Tabs). Navigation controls sit below the tabs
and follow the active tab. Closing the last tab collapses the sidebar
with no lingering webviews or history.