Support GPG signing key configuration

[Valentin-v-Todorov]

GitHub supports GPG signed commits but gh-switch doesn't manage signing keys per profile. Add GPG key field to profiles and set user.signingkey in git config. Need further investigation! Profile should optionally store GPG key ID and configure git to use it. Each profile can have associated GPG signing key

[Z3RO-O]

Hi @Valentin-v-Todorov! I'd like to work on this feature. Here's my implementation plan:

Changes Required:

1. Profile structure - Add GPG_KEY_ID and GPG_SIGN_COMMITS fields

2. New file lib/gpg_utils.sh - GPG validation and key listing functions

3. Update commands:

   • cmd_add - Prompt for GPG key ID (optional)
   • cmd_use - Apply user.signingkey and commit.gpgsign to git config
   • cmd_list/current - Display GPG info

4. Git config integration: - So that when we use gh-switch use personal it should set name, email and GPG key.

5. Backward compatibility - Existing profiles work without GPG fields

6. Documentation - Add GPG setup guide to README

[Valentin-v-Todorov]

LGTM!