chore(kb): downgrade unknown-subblock log to warn; remove per-turn info log

The per-turn 'dynamic-block render: kb-block' INFO line was added for
2e sim verification; with confirmation that the host RPC fires every
turn for every agent, the line becomes noise. Trimmed to keep the
plugin's logs focused on actionable events. The 'unknown name' branch
is now a warn (defensive — shouldn't fire if manifest matches).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
EOF

cmd/plexum-harborforge-plugin/main.go

@@ -230,6 +230,10 @@ func (p *harborForgePlugin) RenderDynamicSubblock(ctx context.Context, agentID,
 	p.agentSession.Store(agentID, sessionID)
 
 	if name != "kb-block" {
+		// Host shouldn't request unknown subblock names per manifest
+		// contract, but log defensively so operator notices wiring drift.
+		p.host.Log("warn", "dynamic-block render: unknown subblock name",
+			map[string]any{"agent": agentID, "session": sessionID, "name": name})
 		return "", nil
 	}
 	block, err := kbblock.Open(p.profileRoot, agentID, sessionID)