refactor(FN-2161): standardize on createFnAgent naming

- Rename engine export and call sites to use createFnAgent consistently across runtime flows
- Update core lazy engine loader and dashboard agent-generation/planning/chat paths to reference createFnAgent
- Refresh affected unit and integration tests, including renaming pi-create-kb-agent.test.ts to pi-create-fn-agent.test.ts
- Update AGENTS.md documentation references to match the new createFnAgent name

packages/core/src/memory-compaction.ts

@@ -79,8 +79,8 @@ export async function compactMemoryWithAi(
   provider?: string,
   modelId?: string
 ): Promise<string> {
-  const createKbAgent = await getKbAgent();
-  if (!createKbAgent) {
+  const createFnAgent = await getKbAgent();
+  if (!createFnAgent) {
     if (DEBUG) console.log("[memory-compaction] AI engine not available");
     throw new AiServiceError("AI engine not available");
   }
@@ -104,7 +104,7 @@ export async function compactMemoryWithAi(
   }
 
   if (DEBUG) console.log("[memory-compaction] Creating agent session...");
-  const agentResult = await createKbAgent(agentOptions);
+  const agentResult = await createFnAgent(agentOptions);
 
   if (!agentResult?.session) {
     if (DEBUG) console.log("[memory-compaction] Failed to initialize AI agent - no session");