Brightencode Launcher v0.1.19

Prefer the worker's icon over the bundle's when both are available

The worker's /icon endpoint is meant to be the single source of truth
for an app's icon — the same iconUrl-or-generated-badge securexe-web's
RepoIcon renders — but install_and_launch had the priority backwards:
it only fetched the worker icon when the downloaded bundle had nothing
extractable. In practice nearly every one of these repos ships some
default framework icon (never customized), so that fallback almost
never triggered, and the gallery ended up showing generic bundled
icons instead of each app's distinct worker badge — visibly out of
sync with the website.

backfill_icons re-syncs every installed app's icon now, not just ones
with nothing cached, so apps that already have a stale bundle-icon
cached from before this fix get corrected too.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>