feat(sdk): expose FloatingAnchor to plugins

Plugins previously had to fake a floating pane by registering into a
chrome slot and rendering position:fixed themselves, which broke inside
any transformed ancestor and reimplemented drag, clamping, and
persistence each time.

apps/desktop/src/sdk/index.ts

@@ -125,6 +125,12 @@ export { type RouteContribution, ROUTES_AREA, SIDEBAR_NAV_AREA, type SidebarNavC
 export type { StatusbarItem } from '@/app/shell/statusbar-controls'
 
 export type { TitlebarTool } from '@/app/shell/titlebar-controls'
+/** Pane placement roles. `'floating'` is the one NON-tiling value: the pane is
+ *  excluded from the layout tree and rendered as a fixed, draggable card above
+ *  it — it takes no width from any zone, has no tab, and can't be docked.
+ *  Pair it with `anchor` (spawn corner, default `'top-right'`) plus
+ *  `width`/`height`. */
+export type { FloatingAnchor } from '@/components/pane-shell/tree/renderer/floating-rect'
 export { StatusDot, type StatusTone } from '@/components/status-dot'
 export { Badge } from '@/components/ui/badge'
 export { Button } from '@/components/ui/button'
@@ -177,6 +183,9 @@ export { Tabs, TabsList, TabsTrigger } from '@/components/ui/tabs'
 export { Textarea } from '@/components/ui/textarea'
 export { Tip, Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from '@/components/ui/tooltip'
 export type { GatewayEventListener } from '@/contrib/events'
+
+// -- contracts ----------------------------------------------------------------
+
 export type {
   HermesPlugin,
   PluginContext,
@@ -184,9 +193,6 @@ export type {
   PluginRestOptions,
   PluginStorage
 } from '@/contrib/plugin'
-
-// -- contracts ----------------------------------------------------------------
-
 /** Mount-scoped contribution: while the rendering component is mounted, its
  *  children render in the target area's slot; unmount disposes it. Use for
  *  page-owned chrome (a page's titlebar control leaves with the page) —
@@ -215,12 +221,12 @@ export { type KeybindContribution, KEYBINDS_AREA } from '@/lib/keybinds/actions'
  *  authors) + its translucent tag fill — so plugin-rendered identities read
  *  the same hue as everywhere else. */
 export { profileColor, profileColorSoft } from '@/lib/profile-color'
+
+export const PANES_AREA = 'panes'
 /** The shared client itself, for invalidation OUTSIDE React (e.g. a
  *  `ctx.socket` frame invalidating a query). Inside components keep using
  *  `useQueryClient`. */
 export { queryClient } from '@/lib/query-client'
-
-export const PANES_AREA = 'panes'
 export const STATUSBAR_AREAS = { left: 'statusBar.left', right: 'statusBar.right' } as const
 export const TITLEBAR_AREAS = { center: 'titleBar.center', left: 'titleBar.left', right: 'titleBar.right' } as const