fix(store): harden persisted saved-role loading

[synsoftworksdev]

Summary

Harden persisted saved-role loading so malformed or partially corrupted role
data fails early and predictably instead of surfacing low-level parse/shape
errors.

Changed

• add InvalidSavedRoleDataError in src/adapters/role-store.ts
• validate saved-role data at load time
• reject:
  • invalid JSON
  • wrong top-level shape
  • malformed role entries
  • bad field types
  • invalid persisted role names
  • mixed valid/invalid entries
• fail the whole load when any persisted role data is invalid
• keep the user-facing error message consistent:
  • saved role data is invalid; fix or recreate the roles file
• add adapter coverage for the invalid persisted-data cases
• update CLI regression coverage for bad saved-role data, including mixed-entry failure

Verification

• npm run build
• npm test
• npm run test:e2e
• npm run test:release

Notes

• no new product features
• no unrelated command/output changes
• commands that load saved roles now fail earlier and more predictably when on-disk role data is invalid