The owner renamed the product and required existing installations to keep
their account, settings and mail.

- Publish as Emc² from 0.1.4, with releases named Emc²-<version>-<os>-<arch>.<ext>.
- Move mail, settings.env and Local State from the pre-rename app-data folder
  into the new one on first launch, marked by .renamed-to-emc2. Local State
  travels because Electron encrypts mail/key.protected with the key it holds;
  without it the moved store cannot be decrypted.
- Keep the Windows application id so an installed copy is upgraded in place.
- Rename the local MCP server to emc2.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>