Add 'thread_shared' event type

Author: pauls-ai2

impl/src/nora_lib/impl/interactions/models.py

@@ -173,6 +173,9 @@ class EventType(Enum):
     # Marks a thread forked from Slack to Web
     THREAD_FORK = "thread_fork"
 
+    # Mark that a thread has been shared with other users
+    THREAD_SHARED = "thread_shared"
+
     # Cost Reporting
     STEP_COST = "step_cost"
     STEP_PROGRESS = "step_progress"