feat(grid-agent): add chat and IM interactions (#123)

config/grid-agent.example.json

@@ -43,5 +43,20 @@
     "max_tool_result_bytes": 16384,
     "max_persisted_bytes": 16777216,
     "max_summary_bytes": 8192
+  },
+  "interaction": {
+    "aliases": ["metacrate"],
+    "debounce_milliseconds": 250,
+    "model_timeout_seconds": 30,
+    "public_rate_milliseconds": 750,
+    "im_rate_milliseconds": 250,
+    "public_followup_seconds": 120,
+    "max_response_bytes": 2048,
+    "grid_chunk_bytes": 1023,
+    "max_active_senders": 512,
+    "max_queued_per_sender": 16,
+    "max_concurrent_inference": 4,
+    "max_duplicate_ids": 4096,
+    "max_debounce_fragments": 8
   }
 }