SDK-1: the parts helper reads the registry part's shapes from a registry seat's module

Interim, for the lead's ruling: ADR 0625 §1 cuts the registry part into each registry seat's own Go module, and §3
lets no mesh-sdk package but catalogue import a contracts module; this helper is logic shared over a seat, a client
in §4's sense, which no clause lets the registry milestone build. Kept building meanwhile.

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

go/publish/publish.go

@@ -1,7 +1,8 @@
 // Package publish is the runtime's helper for sending a file to a registry seat in parts (novox/hq ADR 0611, design
 // 51 *Publishing*): `publish` opens a transfer naming every part's digest, the holder answers the parts it lacks, and
 // only those travel, by `publish-part`, in chunks a bus message carries. A cut transfer goes on from what the holder
-// answers when the same transfer is opened again. The seat's messages are mesh-contracts' (parts/registry); the call is
+// answers when the same transfer is opened again. The seat's messages are mesh-contracts'
+// (the registry part's, read through containerimageregistry, the four registry seats' shapes being one); the call is
 // the caller's own (a bundle's stdio.Ask, a process's call of a seat verb), so this package holds no transport.
 package publish
 
@@ -15,7 +16,7 @@ import (
 	"fmt"
 	"io"
 
-	"git.novox.be/novox/mesh-contracts/go/parts/registry"
+	registry "git.novox.be/novox/mesh-contracts/go/seats/containerimageregistry"
 )
 
 // MaxChunk is the most bytes of a part one publish-part carries: base64 makes it about 1 000 KiB, under 1 MiB, the

go/publish/publish_test.go

@@ -11,7 +11,7 @@ import (
 	"strings"
 	"testing"
 
-	"git.novox.be/novox/mesh-contracts/go/parts/registry"
+	registry "git.novox.be/novox/mesh-contracts/go/seats/containerimageregistry"
 )
 
 // A file travels to a registry seat in parts (ADR 0611, design 51 *Publishing*; SDK-1): only the parts the holder says