feat: live SSE-based Database Activity panel

Replace the static startup-only item list with a real-time event feed:

- InitGui.py: remove the startup list_items() call that showed
  '(Unable to connect)' when not yet authenticated; show a simple
  '(Waiting for connection...)' placeholder instead
- silo_commands.py (submodule): maintain an in-memory event list
  prepended by SSE events, seeded with 10 recent items on first
  connect, with relative timestamps refreshed every 60s

The panel now shows live activity ('F01-0001 updated · just now')
instead of requiring expensive full re-fetches on every SSE event.

src/Mod/Create/InitGui.py

@@ -104,7 +104,7 @@ def _setup_silo_auth_panel():
 
 
 def _setup_silo_activity_panel():
-    """Show a dock widget with recent Silo database activity."""
+    """Show a dock widget with live Silo database activity."""
     try:
         from PySide import QtCore, QtWidgets
 
@@ -121,27 +121,12 @@ def _setup_silo_activity_panel():
 
         widget = QtWidgets.QWidget()
         layout = QtWidgets.QVBoxLayout(widget)
+        layout.setContentsMargins(0, 0, 0, 0)
 
         activity_list = QtWidgets.QListWidget()
+        activity_list.addItem("(Waiting for connection...)")
         layout.addWidget(activity_list)
 
-        try:
-            import silo_commands
-
-            items = silo_commands._client.list_items()
-            if isinstance(items, list):
-                for item in items[:20]:
-                    pn = item.get("part_number", "")
-                    desc = item.get("description", "")
-                    updated = item.get("updated_at", "")
-                    if updated:
-                        updated = updated[:10]
-                    activity_list.addItem(f"{pn} - {desc} - {updated}")
-            if activity_list.count() == 0:
-                activity_list.addItem("(No items in database)")
-        except Exception:
-            activity_list.addItem("(Unable to connect to Silo database)")
-
         panel.setWidget(widget)
         mw.addDockWidget(QtCore.Qt.RightDockWidgetArea, panel)
     except Exception as e: