Fixed

• Web dashboard ignored config.json vault path. web.serve() used
  default_vault_dir() which only checks $ELESYNC_DIR and falls back to
  ~/EleSyncVault — it never read config.json. So if you picked D:\Vault
  during onboarding or ele vault set, the dashboard still used
  ~/EleSyncVault. Now serve() reads config.json when no explicit vault
  is given, matching the CLI's _resolve_vault() behaviour.
• PWA manifest not in pip wheel. static/manifest.json was missing
  from the wheel because package-data only listed *.css, *.js,
  *.png. Added *.json and *.svg so the manifest ships and the web
  app is installable.