feat(ui): portable, resizable rail panels for CCTV

A drag spec can now be `portable`: dragging the panel by its header lifts
it out of the right rail into a fixed window, resizable from all four
edges and corners, that remembers its place and size under the existing
godsEyeView.v8.panelPos.<id> key ({ left, top, width?, height?, floating })
and snaps back on a header double-click. Only CCTV opts in here; the rail
skips .panel-floating panels when measuring and allocating, and its
placement rules in layers.css are guarded so no !important is needed.
PanelPositionControls gains an optional onPanelResized hook, threaded
through PanelChrome to a no-op on the application shell.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/ui/rightPanelRail.js

@@ -41,8 +41,10 @@ export function layoutRightPanelRail({
 }) {
   if (!stack) return;
 
+  // A panel lifted out of the rail (PanelPositionControls' portable mode)
+  // is a fixed window the rail neither measures nor allocates.
   const panels = [...stack.children].filter((panel) =>
-    panel.matches('[data-panel-id]'),
+    panel.matches('[data-panel-id]:not(.panel-floating)'),
   );
   if (!hud.visible || hud.variant !== 'tactical') {
     for (const panel of panels.filter((item) =>