chore/docs: move to GitHub as the single home; drop archived-spec references

Codeberg is being retired as the project's public site, so every reference now
points at GitHub. That includes the Go module path (codeberg.org/mix/selfpost →
github.com/mixeme/selfpost): leaving an import path on a host that is going
away would break `go get` and `go install`, so this is not only a docs change.
Touches go.mod, test/e2e/go.mod, all imports, Makefile MODULE, the -ldflags
version stamp in build/Dockerfile and docs/development.md, the licence headers
in the SVG/HTML assets, and README (no more primary/mirror pair).

Comments no longer cite the archived specification. "spec 7.6.1", "spec 5.1"
and friends pointed into docs/archive/specification-v1.0.md, which is marked as
not a source of truth; each is now a reference to the live document that owns
the subject — architecture.md (with section), product.md, security.md or the
README. The review only asked for the 7.x refs (code-review.md § 4), but 4/5/6/
8/9 had the same defect, so they went too. Comments only, no behaviour change.

Also closes the remaining review items: architecture.md gained a Code layers
section with the layer diagram (A2), and TestParseDelivery gained the exotic
mail.log cases (§ 3).

Fixes a bug that last test found: the delivery-line pattern matched status=
greedily, taking the *last* occurrence on the line. Postfix appends the remote
server's reply verbatim, so a rejection whose reply quoted "status=sent" was
filed as a delivered message in the send log. It now takes the first status=
after the recipient, which is the real field.

R7 (CONTRIBUTING.md) moved to roadmap 2.x — one developer, no external PR flow,
so the file would have no audience yet. R1 (compose image tag) and the git tag
stay in roadmap § v1.x as the release-commit steps.

gofmt/go vet clean on both modules; go test ./... green except the three known
Windows-only failures (file perms, backslash paths, renaming an open file).
Not exercised on the dev server — no Docker locally.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/backup/backup.go

@@ -1,17 +1,18 @@
 // Package backup implements SelfPost's full-server backup and the restore
-// version guard (spec 7.5.A). A full backup is a gzip-compressed tar of the
-// consolidated persistent state under /data — the SQLite database (as a
-// consistent snapshot), the per-domain DKIM keys and the SASL database — plus a
-// manifest recording the SelfPost version that produced it. TLS certificates
-// (the reverse proxy's responsibility) and the Postfix queue are deliberately
-// excluded (spec 7.5.A).
+// version guard (architecture.md § Persistence). A full backup is a
+// gzip-compressed tar of the consolidated persistent state under /data — the
+// SQLite database (as a consistent snapshot), the per-domain DKIM keys and the
+// SASL database — plus a manifest recording the SelfPost version that produced
+// it. TLS certificates (the reverse proxy's responsibility) and the Postfix
+// queue are deliberately excluded (architecture.md § Persistence).
 //
-// Restore is intentionally not a separate code path: a backup is extracted into
-// the /data bind mount before first start, and the panel regenerates Postfix and
-// OpenDKIM from the restored SQLite state exactly as on any normal start. The
-// only restore-specific step is CheckRestore, which refuses to boot if the
-// manifest's version does not match the running binary, so schema/format skew
-// between versions cannot silently corrupt state (spec 7.5.A).
+// Restore is intentionally not a separate code path: a backup is extracted
+// into the /data bind mount before first start, and the panel regenerates
+// Postfix and OpenDKIM from the restored SQLite state exactly as on any normal
+// start. The only restore-specific step is CheckRestore, which refuses to boot
+// if the manifest's version does not match the running binary, so
+// schema/format skew between versions cannot silently corrupt state
+// (architecture.md § Persistence).
 package backup
 
 import (
@@ -39,9 +40,9 @@ const FormatFull = "selfpost-full-backup"
 const ManifestName = "manifest.json"
 
 // Manifest is the small JSON document embedded in every backup archive. Its
-// Version is the single fact that makes restore safe: the panel refuses to boot
-// a data directory whose manifest version does not match its own binary (spec
-// 7.5.A).
+// Version is the single fact that makes restore safe: the panel refuses to
+// boot a data directory whose manifest version does not match its own binary
+// (architecture.md § Persistence).
 type Manifest struct {
 	Format    string `json:"format"`
 	Version   string `json:"version"`
@@ -63,9 +64,9 @@ type Params struct {
 // written under the canonical name; the setup token is transient bootstrap
 // state; a stale manifest from a previous restore must not be re-captured (a
 // fresh one is written instead); and a "tls" directory holds the reverse
-// proxy's certificates, which are explicitly out of scope for a SelfPost backup
-// (spec 7.5.A) — excluding it keeps that guarantee even when an operator points
-// TLS_CERT_FILE inside /data.
+// proxy's certificates, which are explicitly out of scope for a SelfPost
+// backup (architecture.md § Persistence) — excluding it keeps that guarantee
+// even when an operator points TLS_CERT_FILE inside /data.
 var excludedFromArchive = map[string]bool{
 	"selfpost.db":         true,
 	"selfpost.db-wal":     true,
@@ -78,9 +79,10 @@ var excludedFromArchive = map[string]bool{
 
 // Create writes a gzip-compressed tar backup to w. Archive entries are named
 // relative to DataDir, so extracting the archive into the /data bind mount
-// reconstructs the state in place (spec 7.5.A). The SQLite database is added as
-// a consistent snapshot under "selfpost.db"; everything else under DataDir is
-// copied as-is except the entries in excludedFromArchive.
+// reconstructs the state in place (architecture.md § Persistence). The SQLite
+// database is added as a consistent snapshot under "selfpost.db"; everything
+// else under DataDir is copied as-is except the entries in
+// excludedFromArchive.
 func Create(w io.Writer, p Params) error {
 	if p.DataDir == "" || p.DBPath == "" {
 		return fmt.Errorf("backup: DataDir and DBPath are required")
@@ -254,12 +256,13 @@ func snapshotDB(dbPath string) (path string, cleanup func(), err error) {
 	return target, cleanup, nil
 }
 
-// CheckRestore enforces the backup version guard (spec 7.5.A). If manifestPath
-// exists (a backup was extracted into the data directory), its version must
-// match binaryVersion or the panel refuses to start, telling the operator which
-// image tag to use. On a match the manifest is consumed (deleted) so it guards
-// only the first boot after a restore and never blocks a later in-place image
-// upgrade. Absence of the manifest is the normal case and returns nil.
+// CheckRestore enforces the backup version guard (architecture.md §
+// Persistence). If manifestPath exists (a backup was extracted into the data
+// directory), its version must match binaryVersion or the panel refuses to
+// start, telling the operator which image tag to use. On a match the manifest
+// is consumed (deleted) so it guards only the first boot after a restore and
+// never blocks a later in-place image upgrade. Absence of the manifest is the
+// normal case and returns nil.
 func CheckRestore(manifestPath, binaryVersion string) error {
 	data, err := os.ReadFile(manifestPath)
 	if os.IsNotExist(err) {

internal/backup/backup_test.go

@@ -11,7 +11,7 @@ import (
 	"strings"
 	"testing"
 
-	"codeberg.org/mix/selfpost/internal/store"
+	"github.com/mixeme/selfpost/internal/store"
 )
 
 // seedDataDir builds a realistic /data tree: a migrated SQLite database plus the