feat: add order property to VaultEntry and install @dnd-kit

- Add `order: number | null` to VaultEntry (TS) and VaultEntry (Rust)
- Add order to Frontmatter struct and SKIP_KEYS in vault.rs
- Update all mock Type documents with order values (0-10)
- Add order: null to all non-Type mock entries and test fixtures
- Install @dnd-kit/core, @dnd-kit/sortable, @dnd-kit/utilities

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

src/hooks/useNoteActions.ts

@@ -214,7 +214,7 @@ export function useNoteActions(
       aliases: [], belongsTo: [], relatedTo: [],
       status: noStatusTypes.has(type) ? null : 'Active',
       owner: null, cadence: null, archived: false, modifiedAt: now, createdAt: now, fileSize: 0,
-      snippet: '', relationships: {}, icon: null, color: null,
+      snippet: '', relationships: {}, icon: null, color: null, order: null,
     }
 
     const frontmatter = [
@@ -242,7 +242,7 @@ export function useNoteActions(
       aliases: [], belongsTo: [], relatedTo: [],
       status: null, owner: null, cadence: null, archived: false,
       modifiedAt: now, createdAt: now, fileSize: 0,
-      snippet: '', relationships: {}, icon: null, color: null,
+      snippet: '', relationships: {}, icon: null, color: null, order: null,
     }
 
     const content = `---\nIs A: Type\n---\n\n# ${typeName}\n\n`