createInlineAiPopover() mounts a floating toolbar anchored to the
current text selection. Three actions (Rewrite / Shorten / Expand)
plus loading spinner with cancel, and an error state with retry and
dismiss. Click handlers dispatch via onAction/onCancel/onRetry.
Positioning flips below the line if there is no room above and
clamps horizontally so the popover stays inside the viewport.
16 new tests covering mount/visibility, idle actions dispatching the
selection text, state transitions (idle / loading / error), Retry
and Dismiss callbacks, and positioning edge cases.
Amit Haridas
