chore(flatpak): expect BlueShell and Ghostty in the remote

[hanthor]

Follow-up to #373. Both terminals are in the index now — BlueShell since the repo moved into the org, Ghostty as of today's first publish (tuna-os/blueshell#83) — so check-flatpak-remote.py has been emitting:

WARN: index/static has 2 app(s) not in expected-apps.json (new app? add it): ['tuna-os/blueshell', 'tuna-os/ghostty']

Listing them turns that standing warning into a real check: from here on, either app dropping out of the index — or losing an architecture — fails the sanity job instead of passing quietly.

This is deliberately a follow-up rather than part of #373: check_index fails on an app listed here but absent from the index, so it could not land until Ghostty's entry actually existed.

ghostty carries issue_repo: tuna-os/blueshell because tuna-os/ghostty is a registry path, not a repository — the app is built and published from tuna-os/blueshell through the reusable pipeline's source-repo input, so that's where the smoke test should file.

Verification

$ python3 .github/scripts/check-flatpak-remote.py
OK -- 0 warning(s), no errors.

$ flatpak install --user -y tuna-os com.mitchellh.ghostty
Installation complete.

$ flatpak info com.mitchellh.ghostty
   Ref: app/com.mitchellh.ghostty/x86_64/master
Origin: tuna-os

$ flatpak run com.mitchellh.ghostty --version
Ghostty 1.3.2-main-+492300c

🤖 Generated with Claude Code

https://claude.ai/code/session_01EMBRswEeeX2kzVSwpbxCoy