feat(agent): unify MCP tools and adopt Responses delivery

Move project and host queries into native MCP with host-owned OAuth/context,
while retaining memory, skills, actions and publication plugins. Add nearby-model
queries and explicit chat/task/learning model defaults.

Adopt Responses HTTP/SSE and native steer/queue inbox delivery, preserving scoped
session ownership, pending input edits and investigation communication.

Disable local-provider discovery: Server /health allowed native vLLM to probe
/v1/models on port 8000. A native before/after regression prevents recurrence.

Validation: 170 focused Bun tests; service/plugin typechecks; native discovery,
provider-discovery and input-inbox smoke checks; no paid model inference.

src/routes/chatSession.ts

@@ -160,7 +160,7 @@ export const generateSessionTitle = async (
     return fallback;
   } finally {
     if (titleSessionId) {
-      await runtime.abortSession(titleSessionId).catch((error) => {
+      await runtime.removeSession(titleSessionId).catch((error) => {
         logger.debug({ sessionId: titleSessionId, err: error }, "failed to cleanup title session");
       });
     }