Sign-out, category links, and language switching no longer trip over each other

This release closes three reader-facing bugs that were quietly hurting the experience.

• Sign-out used to land users on a redirect chain that occasionally settled on the wrong host. It now reliably routes back to the admin sign-in.
• Category links were broken on certain layouts because the project slug wasn't being threaded through, leaving readers staring at a 404.
• The hreflang tags emitted on multilingual pages no longer point to malformed URLs, which means search engines can finally pair the English and Spanish versions of your articles correctly.

Each of these individually was easy to miss, but together they were the kind of papercuts that erode reader confidence on a public blog. All three are fixed in the same release.