MV1: move contracts and sdk under modules/, importers follow

The delivery repository's contracts and SDK live under modules/ as
mesh-delivery-contracts and mesh-delivery-sdk, their Go module paths
renamed to match the folders (the TypeScript names already did), and
every importer in mesh-delivery, mesh-catalog, mesh-host, mesh-tools
and mesh-sdk follows in the same group: a design as it should be, one
path per module, checked by the group's check building every importer.

Builds: design 47 G §427, §88

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

modules/mesh-delivery-checker/cmd/mesh-checking-program/main.go

@@ -19,7 +19,7 @@ import (
 
 	"mesh-delivery-checker/rules"
 
-	"git.novox.be/novox/mesh-delivery/sdk/buildstep"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-sdk/buildstep"
 )
 
 func main() {

modules/mesh-delivery-checker/cmd/mesh-checking-program/main_test.go

@@ -15,9 +15,9 @@ import (
 
 	"mesh-delivery-checker/rules"
 
-	"git.novox.be/novox/mesh-delivery/contracts/go/clients/meshdeliverycheckerclient"
-	"git.novox.be/novox/mesh-delivery/sdk/buildstep"
-	"git.novox.be/novox/mesh-delivery/sdk/seatdefs"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-contracts/go/clients/meshdeliverycheckerclient"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-sdk/buildstep"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-sdk/seatdefs"
 	"git.novox.be/novox/mesh-sdk/go/seatdef"
 )