fix: preserve cockpit steps across view toggles and show full step info

Backend: stop wiping pending_task_lane when AI response has no new
[ACTIONS]/[QUESTIONS] markers — previous task lane state is still
relevant until replaced by new markers.

Frontend (selectChat): don't eagerly clear task lane before server
response arrives; restore from sessionStorage as fallback when
pending_task_lane is null (covers sessions before backend fix).

StepsPanel: show description and command for all steps instead of
hiding behind hover/active-only visibility. Commands render as
inline code blocks.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/services/unified_chat_service.py

@@ -339,14 +339,12 @@ async def send_chat_message(
                 except Exception:
                     logger.exception("Failed to create fork within branch for session %s", session.id)
 
-            # Persist task lane state on session
+            # Persist task lane state on session — only overwrite when new markers present
             if branch_questions_data or branch_actions_data:
                 session.pending_task_lane = {
                     "questions": branch_questions_data or [],
                     "actions": branch_actions_data or [],
                 }
-            else:
-                session.pending_task_lane = None
 
             suggested_flows = extract_suggested_flows(
                 await rag_search(query=message, account_id=account_id, db=db, limit=8)
@@ -472,14 +470,12 @@ async def send_chat_message(
             logger.exception("Failed to create fork for session %s", session_id)
             # Fork failed but chat message still sent — don't break the response
 
-    # Persist task lane state on session
+    # Persist task lane state on session — only overwrite when new markers present
     if questions_data or actions_data:
         session.pending_task_lane = {
             "questions": questions_data or [],
             "actions": actions_data or [],
         }
-    else:
-        session.pending_task_lane = None
 
     suggested_flows = extract_suggested_flows(rag_results)