docs(tooltip): add dedicated mdx docs for TooltipSimple

[rinkydevi]

Closes #268

Changes

• Added tooltip-simple.mdx — a dedicated Storybook docs page for
  TooltipSimple with sections for basic usage, arrow, positioning,
  delay duration, controlled mode, inside a modal, extra content props,
  and a live Props table.
• Updated tooltip.mdx to focus solely on primitive composition
  (TooltipRoot, TooltipTrigger, TooltipContent). Replaced the
  embedded TooltipSimple section with a cross-link to the new page.
• Renamed the story category from Composed Components/Tooltip/TooltipSimple
  to Composed Components/TooltipSimple — removes the double-nesting
  in the sidebar.
• Added tooltipContentProps to the Storybook controls table with an
  accurate type summary and description.

Evidence

Screen.Recording.2026-06-05.at.6.41.50.PM.mov

How to test

pnpm --filter docs dev                                                                                                  
                                                                                                               
1. Open Storybook → Composed Components > TooltipSimple — should show the
new dedicated docs page with live demo and Props table.                                                               
2. Open Primitive Components > Tooltip — should only cover primitive
composition, with a link at the top pointing to TooltipSimple.
3. Confirm TooltipSimple no longer appears nested under Tooltip in
the sidebar.