Point at the Coffey-Labs organisation

The repositories moved off LINUXexpert-org. The old URLs redirect, so
nothing was broken, but a redirect is not a correct address to publish.

The SOURCE_URL defaults matter most: the AGPL asks whoever runs a
modified version to offer that version's source, and the sign-in page and
About screen show this link. It is in four places that have to agree --
the compose file, .env.example, the server default and the web fallback.

The rest is documentation and issue links.

server/src/version.test.ts

@@ -10,7 +10,7 @@ import { formatVersion, resolveVersion, UNVERSIONED, versionFromGit } from "../.
 
 test("a pull request merge is named by its number", () => {
   assert.equal(
-    formatVersion({ date: "2026-08-30", subject: "Merge pull request #129 from LINUXexpert-org/link-project-site-v2", sha: "1fa6578" }),
+    formatVersion({ date: "2026-08-30", subject: "Merge pull request #129 from Coffey-Labs/link-project-site-v2", sha: "1fa6578" }),
     "2026.8.30+pr129",
   );
 });