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/repo/store/userRepo.store.ts

@@ -1,6 +1,6 @@
 import { defineStore } from "pinia"
 
-import { data } from "@/data/data"
+import { data, generateId } from "@/data/data"
 import { DataType } from "@/data/DataType.enum"
 import { RepoFile } from "@/modules/repo/interfaces/RepoFile"
 import { UserSettings } from "@/modules/repo/interfaces/UserSettings"
@@ -39,7 +39,7 @@ export const useUserRepoStore = defineStore("USER_REPO_STATE", {
       this.user = user
       this.repo = repo
 
-      const savedRepoId = data.generateId(DataType.SavedRepo, `${user}-${repo}`)
+      const savedRepoId = generateId(DataType.SavedRepo, `${user}-${repo}`)
       const userSettingsId = `UserSetting-${user}-${repo}`
 
       const [cachedSavedRepo, cachedUserSettings] = await Promise.all([
@@ -131,7 +131,7 @@ export const useUserRepoStore = defineStore("USER_REPO_STATE", {
         return
       }
 
-      const savedRepoId = data.generateId(
+      const savedRepoId = generateId(
         DataType.SavedRepo,
         `${this.user}-${this.repo}`
       )