perf: move PouchDB/IndexedDB operations to a Web Worker

All database reads and writes now run off the main thread via a
dedicated worker, eliminating IndexedDB overhead from the frame budget.

- Create data.worker.ts exposing the Data class via Comlink
- Refactor data.ts to export a Comlink-wrapped proxy and a standalone
  generateId() pure function (workers can't expose sync methods cleanly)
- Update all 10 call sites to import generateId directly instead of
  calling data.generateId()

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

src/modules/history/hooks/useVisitRepo.hook.ts

@@ -1,10 +1,10 @@
 import { Ref, toValue } from "vue"
 
-import { data } from "@/data/data"
+import { data, generateId } from "@/data/data"
 import { DataType } from "@/data/DataType.enum"
 import { History } from "@/data/models/History"
 
-const HISTORY_ID = data.generateId(DataType.History, "history")
+const HISTORY_ID = generateId(DataType.History, "history")
 const MAX_REPO_HISTORY = 10
 
 export const useVisitRepo = (newRepo: {