Adds new integration [j9brown/victron-mk3-hass]

[j9brown]

Checklist

• I've read the publishing documentation.
• I've added the HACS action to my repository.
• (For integrations only) I've added the hassfest action to my repository.
• The actions are passing without any disabled checks in my repository.
• I've added a link to the action run on my repository below in the links section.
• I've created a new release of the repository after the validation actions were run successfully.

Links

Link to current release: https://github.com/j9brown/victron-mk3-hacs/releases/tag/v0.4.3
Link to successful HACS action (without the ignore key): https://github.com/j9brown/victron-mk3-hass/actions/runs/11138684640
Link to successful hassfest action (if integration): https://github.com/j9brown/victron-mk3-hass/actions/runs/11138684651

[hacs-bot]

Do not use 'HACS' as a part of your repository name.