refactor(embed): drop dead Embedded.HTTPAddr accessor

Provably-dead exported accessor: no in-repo callers (only cmd/kmsd and
mount.go consume the root package) and no external importer of
github.com/hanzoai/kms across the tree uses it. Its backing httpAddr
field was write-only and its comment was wrong (stored the raw config
addr, never a resolved listener address). Removes field, assignment,
and accessor. Build+vet green.

embed.go

@@ -133,8 +133,6 @@ type Embedded struct {
 	replicator  *badger.Replicator
 	auditCancel context.CancelFunc
 	zapNode     *zap.Node // nil when ZAP server disabled
-
-	httpAddr string // bound listener address (post-:0 resolution)
 }
 
 // Embed boots the Hanzo KMS server in-process and returns a handle.
@@ -237,7 +235,6 @@ func Embed(ctx context.Context, cfg EmbedConfig) (*Embedded, error) {
 			WriteTimeout:      60 * time.Second,
 			IdleTimeout:       120 * time.Second,
 		}
-		em.httpAddr = cfg.HTTPAddr
 		go func() {
 			log.Info("kms.Embed: HTTP listening", "addr", cfg.HTTPAddr)
 			if err := em.httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
@@ -264,15 +261,6 @@ func (e *Embedded) HTTPHandler() http.Handler {
 	return e.handler
 }
 
-// HTTPAddr returns the bound listen address. Returns "" when
-// SkipListen=true or before the listener has been wired.
-func (e *Embedded) HTTPAddr() string {
-	if e == nil || e.cfg.SkipListen {
-		return ""
-	}
-	return e.httpAddr
-}
-
 // ZAPPort returns the ZAP secrets-server port (0 when disabled).
 func (e *Embedded) ZAPPort() int {
 	if e == nil || e.zapNode == nil {