CI: stage bakery from signed stable index, drop bread-theme cargo build

The tagged ISO workflow fetched bos-settings/src/Cargo.toml from the
dev branch (404 after the Tauri split) and cargo-built bread-theme.
bread-theme 0.7.1 is already on the stable index. Stage required bins,
units, breadhelp content, and desktop/license files from the
minisign-verified index instead; optional bread-emit/module-host skip
until bread publishes them. Fail the bake if a required bin is missing.

.gitignore

@@ -44,3 +44,8 @@ logs/
 /Bread Background.png
 
 # Local hygiene notes (not for commit)
+CLAUDE.md
+
+# Python
+__pycache__/
+*.pyc