fix: use ExperienceDimensionKeyMap and narrow slots union in FragmentProps

- Replace inline dimensionKeyMap struct with ExperienceDimensionKeyMap (shared
  named type from experience.ts, mirrors upstream DimensionKeyMap)
- Drop TreeNode from slots union — upstream contract (experienceCommonFields)
  uses ViewNode | FragmentNode | InlineFragmentNode; SDK drops deprecated ViewNode
  leaving FragmentNode | InlineFragmentNode, matching ExperienceProps.slots exactly
- Remove unused TreeNode import from component-type

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: tylerpina

lib/entities/fragment.ts

@@ -9,9 +9,8 @@ import type {
   ComponentTypeViewport,
   DimensionedDesignPropertyValue,
   FragmentNode,
-  TreeNode,
 } from './component-type'
-import type { ExperienceContentBindings, InlineFragmentNode } from './experience'
+import type { ExperienceContentBindings, ExperienceDimensionKeyMap, InlineFragmentNode } from './experience'
 
 export type FragmentSys = {
   id: string
@@ -44,10 +43,10 @@ export type FragmentProps = {
   description: string
   viewports: ComponentTypeViewport[]
   designProperties: Record<string, DimensionedDesignPropertyValue>
-  dimensionKeyMap: { designProperties: Record<string, { breakpoint: string }> }
+  dimensionKeyMap: ExperienceDimensionKeyMap
   contentBindings?: ExperienceContentBindings
   metadata?: ExoMetadataProps
-  slots?: Record<string, Array<TreeNode | FragmentNode | InlineFragmentNode>>
+  slots?: Record<string, Array<FragmentNode | InlineFragmentNode>>
 }
 
 export type CreateFragmentProps = Except<FragmentProps, 'sys'> & {