Point links at the new git host

GitHub went dark with the account suspension on 2026-09-20 and GitLab was
retired on 2026-09-22, so links to either no longer resolve. Repository,
file, release and download links now point at git.coffeylabs.org, images
at registry.coffeylabs.org, and old GitHub issue and pull request links at
coffey-labs/ihasmail-github-archive, whose numbers match GitHub's.

server/src/config.ts

@@ -280,7 +280,7 @@ export const config = {
    * source, not the one it was forked from -- so anyone deploying a patched
    * ihasmail should point this at their own tree.
    */
-  sourceUrl: env("SOURCE_URL", "https://github.com/Coffey-Labs/ihasmail"),
+  sourceUrl: env("SOURCE_URL", "https://git.coffeylabs.org/coffey-labs/ihasmail"),
   host: env("HOST", "0.0.0.0"),
   port: int("PORT", 8080),
   /**