A failed fetch fell back to the cached value with no limit, so an unreachable
blog API kept the post list rendering while every uncached slug returned 404.
Stale entries now survive an hour past their TTL, then get dropped and logged
at error so the outage surfaces the same way for every key.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
BlogService now fetches from Media.JoshHeaps.Net API via HttpClient
with in-memory caching (5-min TTL) and stale cache fallback.
Removed Markdig/YamlDotNet dependencies. All page models now async.
Co-Authored-By: Claude Opus 4.6 <[email protected]>