Rename mesh-control -> mesh-controller, substrate -> foundation

One name per thing, per the HQ glossary: the module/container/image/binary/repo
becomes mesh-controller, the seat the-controller, and the store+broker pair the
foundation (embedded base bundles, default template and example lock renamed with
their go:embed directives). No behaviour change — a pure vocabulary rename.

Claude-Session: https://claude.ai/code/session_01D6qtiYU3P9jk3pnAXyAFyx

internal/link/heard_test.go

@@ -5,8 +5,8 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/novox/mesh-control/internal/inventory"
-	"github.com/novox/mesh-control/internal/link"
+	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/link"
 )
 
 // Turning what a node said into what the mesh keeps.
@@ -152,7 +152,7 @@ func TestABareAliveDoesNotWipeTheDeclarationThatSaysANodeIsCurrent(t *testing.T)
 func TestAFailureDoesNotBecomeTheAccountOfWhatTheMachineHolds(t *testing.T) {
 	// A partial list is not an account of what the machine holds. Recording one as though it
 	// were would tell a rebuilding node to remove what it still has — which is the fault that
-	// destroyed a substrate once (novox/hq 04-ISSUES/010).
+	// destroyed a foundation once (novox/hq 04-ISSUES/010).
 	inv := inventory.ForTest(t)
 	ctx := context.Background()
 	node, err := inv.AddNode(ctx, "workstation")