Verify the Flatpak

If possible, please consider [verifying](https://docs.flathub.org/docs/for-app-authors/verification) this Flatpak to give it more credibility and make it appear in distributions such as Linux Mint (that hide unverified apps by default).

Start with the linked Flathub verification documentation and review the requirements for verifying this app. Complete the verification process for ai.opencode.opencode; done means the Flatpak is marked verified and can appear in distributions such as Linux Mint that hide unverified apps.

索引モデルが issue の本文から書いたものです。