fix(page): fully end drag on webview mouseup to prevent overlay blocking clicks
The __PEEK_MOUSEUP__ handler only set pageMouseButtonDown=false when a drag
was active, relying on a subsequent document mousemove to detect the stale
isDragging flag and clean up the drag overlay. If no mousemove occurred (e.g.
a quick click without movement), the drag overlay remained active with
pointer-events:all, blocking all subsequent clicks on the webview content.
This caused YouTube pause buttons and other interactive elements to become
unclickable after the hold-to-drag timer fired during a quick click (race
condition between the 80ms timer and async IPC mouseup delivery).
Now the mouseup handler fully resets drag state: isDragging, overlay class,
cursor styles, and URL params — matching the cleanup in the document mouseup
handler.