chore: delete dead kernel Go code

Remove orphaned channel/message type comments from interfaces.go,
unused roleFilterType() function from pages.go, and stale version
comment from main.go.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/main.go

@@ -59,13 +59,10 @@ func main() {
 	// ── Server startup ──────────────────────
 	cfg := config.Load()
 
-	// v0.33.0: Structured logging — must be first so all subsequent
+	// Structured logging — must be first so all subsequent
 	// log output goes through slog.
 	logging.Init(cfg.LogFormat, cfg.LogLevel)
 
-
-	// v0.29.1: Config-file provider types (Ollama, LiteLLM, vLLM, etc.)
-
 	var stores store.Stores
 	uekCache := crypto.NewUEKCache()
 	var keyResolver *crypto.KeyResolver