Channels tab drag-to-reorder, Namespace absolute references, fix stale Channel ID renames

Generalized the Plot pane drag-to-reorder (_PaneDragHandle/_PlotDropContainer
-> _DragHandle/_DragReorderContainer) and reused it for the Channels tab's
derived-channel list; reordering also updates SignalProcessor's evaluation
order (list order matters for chained Channels) via new reorder_derived().

Namespace panel: added an ID column (bare channel_id, matching the actual
channels.get(...) script convention) and fixed the Source column for
Channels to show resolved absolute references (dev_id/ch_id for a Signal,
bare id for a chained Channel) instead of the operation kind, so a chain
is traceable by eye.

Fixed a real bug this surfaced: renaming a Channel's ID never propagated
to other Channels' sources, leaving dangling ("derived", old_id)
references that silently stopped updating. Added
SignalProcessor.rename_derived() to fix up sources plus carry the ring
buffer/latest-value cache to the new key, wired to DerivedBlock's Apply.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/ui/windows/config_window.py b/ui/windows/config_window.py
index 3bd3dc6..34cc789 100644
--- a/ui/windows/config_window.py
+++ b/ui/windows/config_window.py
@@ -34,7 +34,7 @@ from ui.windows.devices_window import DeviceRow, ChannelsTab
 from ui.windows.channels_window import PipelineTab, _slug_id, _dedupe_name
 from ui.windows.plot_window import (
     PlotWindow, LayoutConfig, LayoutCanvas, PaneBlock,
-    build_default_layout, _PlotDropContainer,
+    build_default_layout, _DragReorderContainer,
 )
 from ui.namespace_panel import NamespacePanel
 
@@ -242,7 +242,7 @@ class _PlotTab(PlotWindow):
 
         scroll = QScrollArea(); scroll.setWidgetResizable(True)
         scroll.setObjectName("deviceScroll")
-        self._cont = _PlotDropContainer(self)
+        self._cont = _DragReorderContainer(self)
         self._blay = QVBoxLayout(self._cont)
         self._blay.setContentsMargins(10, 10, 10, 10); self._blay.setSpacing(12)
         self._blay.addStretch()