Point links at git.coffeylabs.org after the move from GitHub

GitHub took the organization's repos and GHCR offline on 2026-09-20. Repo,
release, raw-file and clone links now go to Gitea at git.coffeylabs.org,
container images to registry.coffeylabs.org, and GitLab-style /-/blob paths
to Gitea's /src/branch form. Go module paths are identifiers and stay as
they are; links to GitHub issues and pull requests are left as history.

internal/config/config.go

@@ -37,7 +37,7 @@ const (
 	DefaultStalwartImage = "stalwartlabs/stalwart:v0.16.22"
 	DefaultCaddyImage    = "caddy:2.11.4"
 
-	IhasmailRepository = "ghcr.io/coffey-labs/ihasmail"
+	IhasmailRepository = "registry.coffeylabs.org/coffey-labs/ihasmail"
 	// NewestIhasmail is the default --ihasmail-image. Only full releases move
 	// this tag; prereleases never do.
 	NewestIhasmail = IhasmailRepository + ":latest"

internal/config/config_test.go

@@ -104,17 +104,17 @@ func TestIhasmailFollowsTheNewestReleaseUnlessNamed(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !p.FollowsNewestIhasmail() || p.IhasmailImage != "ghcr.io/coffey-labs/ihasmail:latest" {
+	if !p.FollowsNewestIhasmail() || p.IhasmailImage != "registry.coffeylabs.org/coffey-labs/ihasmail:latest" {
 		t.Errorf("default ihasmail image %q", p.IhasmailImage)
 	}
-	named, err := Options{Domain: "example.com", IhasmailImage: "ghcr.io/coffey-labs/ihasmail:2026.9.13-pr344"}.Validate()
+	named, err := Options{Domain: "example.com", IhasmailImage: "registry.coffeylabs.org/coffey-labs/ihasmail:2026.9.13-pr344"}.Validate()
 	if err != nil {
 		t.Fatal(err)
 	}
 	if named.FollowsNewestIhasmail() {
 		t.Error("a named image is treated as the newest release")
 	}
-	byDigest := "ghcr.io/coffey-labs/ihasmail@sha256:" + strings.Repeat("a", 64)
+	byDigest := "registry.coffeylabs.org/coffey-labs/ihasmail@sha256:" + strings.Repeat("a", 64)
 	if _, err := (Options{Domain: "example.com", IhasmailImage: byDigest}).Validate(); err != nil {
 		t.Errorf("a by-digest image is refused: %v", err)
 	}

internal/docker/docker.go

@@ -66,7 +66,7 @@ func envValue(env, name string) string {
 }
 
 // RepoDigest is an image's by-digest reference in one repository, e.g.
-// ghcr.io/coffey-labs/ihasmail@sha256:..., which names exactly that image for
+// registry.coffeylabs.org/coffey-labs/ihasmail@sha256:..., which names exactly that image for
 // as long as the registry keeps it.
 func RepoDigest(ctx context.Context, image, repository string) (string, error) {
 	out, err := Output(ctx, "image", "inspect", "--format", "{{range .RepoDigests}}{{println .}}{{end}}", image)