The dynamic /blog/rss.xml returned 500 in CI (no Supabase env) and the E2E
still asserted the old static feed's hand-written items.
- /blog, /blog/[slug], and /blog/rss.xml now degrade gracefully (empty feed/
list, HTTP 200) when Supabase is unavailable, instead of throwing.
- E2E: assert the always-present channel <title>LogicSRC Blog</title> and a
looser xml content-type, dropping the removed static post titles.
Verified with `next dev` and no Supabase env (CI conditions): rss/blog/sitemap
all return 200.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
