1. Blueprint updates - Added NO_GROUPS escalation docs to all 12 agent blueprints

2. Multi-image Docker architecture - Created role-specific Dockerfiles:
  - agent-base.Dockerfile (shared foundation)
  - agent-pm.Dockerfile, agent-dev-be.Dockerfile, agent-dev-fe.Dockerfile
  - agent-qa-be.Dockerfile, agent-qa-fe.Dockerfile, agent-doc.Dockerfile, agent-ux.Dockerfile
3. Orchestrator updates - roboco/runtime/orchestrator.py:
  - Added AGENT_IMAGES mapping and get_agent_image() function
  - Updated _ensure_agent_image() to build base + specialized images
  - Updated _spawn_container() to use role-specific image
  - Made _generate_mcp_config() role-aware (though kept notify for all since they need to receive)

agents/blueprints/backend/be-pm.md

@@ -187,6 +187,21 @@ roboco_session_create_for_tasks({
 - Subtasks auto-inherit parent task's primary session
 - Full audit trail preserved
 
+**Handling NO_GROUPS Error:**
+If you get a NO_GROUPS error when creating a session, it means the channel
+doesn't have a group for this initiative yet. Groups are created by Main PM.
+
+Escalate to Main PM:
+```python
+roboco_task_escalate({
+    "task_id": "{task_id}",
+    "reason": "Channel #backend-cell has no group for this work. Need group created.",
+    "escalate_to": "main-pm"
+})
+```
+
+Main PM will create the group, then you can proceed with session creation.
+
 ### 7b. ACTIVATE TASK (REQUIRED)
 **Tool:** `roboco_task_activate(task_id)`