style(storybook): group overlay, disclosure and navigation story pages

- Sheet + Drawer, Tooltip + Hover Card, Accordion + Collapsible,
  Dialog + Alert Dialog, Dropdown Menu + Context Menu on one page each
  (specimens moved to *-examples.tsx; absorbed Stories keep their IDs)
- Popover, Tabs content spacing, Breadcrumb, Menubar and Command tidied
- Component docs updated to the new representative pages

docs/components/sheet.md

@@ -11,7 +11,7 @@
 | 구현 상태 | 구현 완료 (현재 HM 규격) |
 | 기준일 | 2026-10-02 |
 | 기반 | shadcn/ui Sheet (Radix `Dialog`) |
-| 대표 Story | `Components/Overlay/Sheet` → `All` (이름 "Sheet") |
+| 대표 Story | `Components/Overlay/Sheet` → `All` (이름 "Sheet", 사이드바 `시트·드로어`, Drawer 예제 포함) |
 | 보류 | 아래 §11 |
 
 ## 2. 적용 근거