feat(writing): token-usage in version history + draft drag-source

Two small UX wins.

Version-history shows generation cost
- VersionHistory takes a generations[] prop (DetailView already pulls
  one via useGenerationsForDraft) and looks up each AI version's linked
  Generation by id. When found, renders a monospace cost line under the
  version's wordcount: "1234 → 567 Tokens · 1.4s · ollama/gemma3:4b".
- Skips silently when the generation row isn't there (e.g. older drafts
  before the field was tracked, or a generation that was reverted).
- Lets the user see what each draft cost without digging into the
  Workbench audit timeline.

Drafts as drag source
- DraftCard wires `use:dragSource` with type='draft' + a payload
  carrying id / title / kind / content / wordCount / topic. Cards in
  the Writing list view are now drag origins for any drop target that
  declares acceptsDropFrom: ['draft'].
- App-registry entry for 'writing' gets the matching collection /
  paramKey / dragType / getDisplayData fields so the workbench layer
  treats drafts as full first-class drag-citizens (sibling navigation,
  display fallbacks).
- @mana/shared-ui DragType union extended with 'draft'.

No drop-target wiring yet — articles' acceptsDropFrom can pick up
'draft' as a follow-up, but the M10 ExportMenu's "Als Artikel
speichern" already covers that flow from the editor side.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shared-ui/src/dnd/types.ts

@@ -27,7 +27,8 @@ export type DragType =
 	| 'dream'
 	| 'journal-entry'
 	| 'first'
-	| 'wish';
+	| 'wish'
+	| 'draft';
 
 export interface DragPayload<T = Record<string, unknown>> {
 	type: DragType;