[Feature]: Add spellcheck language selection and a disable option

[MIOsystems]

Problem

Hermes One currently marks Dutch text as misspelled, even though Windows 11 is configured to support both Dutch and English spelling.

There is no visible setting to:

• select the spellcheck language;
• enable multiple spellcheck languages;
• use the languages configured in the operating system;
• disable spellchecking completely.

This makes the chat composer distracting for multilingual users because correctly written Dutch text receives red underlines.

Current behavior

The chat composer uses the spellchecker provided by Electron/Chromium, but Hermes One does not expose any spellcheck preferences.

The active dictionary appears to be limited to one language and does not reflect all languages configured in Windows.

Requested behavior

Add spellcheck controls to Settings, preferably under Language or a new Chat section:

• Enable spellcheck toggle;
• Use system languages option;
• multi-select language list, for example:
  • nl-NL
  • en-US
• persist the selection between application restarts;
• apply the setting to the main chat composer and any other editable message fields.

At minimum, users should be able to disable spellchecking completely.

Suggested implementation

Electron supports enabling multiple dictionaries through:

session.defaultSession.setSpellCheckerLanguages([
  "nl-NL",
  "en-US",
]);

The selected languages should first be checked against availableSpellCheckerLanguages.

Expected result

A multilingual user can enable Dutch and English simultaneously, or turn spellchecking off entirely.

Environment

• Hermes One: latest version
• Operating system: Windows 11
• Connection mode: remote Hermes server