fix: migrate semantic-release from GitHub to Gitea

- Replace @semantic-release/github with @saithodev/semantic-release-gitea
- Configure giteaUrl for git.debyl.io
- Use Gitea's automatic GITHUB_TOKEN as GITEA_TOKEN
- Set git author/committer for bot commits

.releaserc.json

@@ -27,7 +27,12 @@
         "changelogFile": "CHANGELOG.md"
       }
     ],
-    "@semantic-release/github",
+    [
+      "@saithodev/semantic-release-gitea",
+      {
+        "giteaUrl": "https://git.debyl.io"
+      }
+    ],
     [
       "@semantic-release/git",
       {