refactor(ui): remove floating, resizable rail panels

PR #768 bundled a portable-panel windowing system with the Street Level
layer. Remove it so CCTV and Street Level are ordinary docked right-rail
panels again, as on main before the merge.

Removed:
- header drag to float, 8-way edge/corner resize, double-press snap-back,
  dockOnCollapse, command-dock clearance, float hint toast, floating z floor,
  persisted floating geometry and ResizeObserver re-clamping
  (panelPositionControls.js restored to its pre-#768 version)
- src/ui/panelResize.js and its tests, panelDock.test.mjs
- onPanelResized/dockPanel wiring in PanelChrome, the application shell and
  StreetLevelControls (EXPAND/SHRINK no longer docks)
- :not(.panel-floating) guards and .panel-floating/.panel-portable/resize CSS
- qa:panel-resize, qa-panel-resize.mjs, qa-panelDrag.mjs, their tests, the
  CI "Portable panel gate" step, QA_FAIL_ON_RETRY, and the Street Level
  gate's float/resize/dock steps
- floating-panel docs in README, CHANGELOG, CURRENT-STATE, KNOWN-ISSUES

Kept: the Street Level panel as a docked rail panel (share/cockpit/rail
lists, layout controller, rail and Cyber CSS, EXPAND viewer), and the
independent right-rail alignment fix (settledLeftRailTop, 9dde7b4).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/ui/styles/layers.css

@@ -161,8 +161,8 @@
     max-height var(--transition-fast);
 }
 #right-context-rail > #pp-toggles,
-#right-context-rail > #cctv-panel:not(.panel-floating),
-#right-context-rail > #street-level-panel:not(.panel-floating),
+#right-context-rail > #cctv-panel,
+#right-context-rail > #street-level-panel,
 #right-context-rail > #weather-panel,
 #right-context-rail > #recent-imagery-panel,
 #right-context-rail > #global-context-panel {
@@ -176,8 +176,8 @@
   max-height: 100%;
   pointer-events: auto;
 }
-#right-context-rail #cctv-panel:not(.panel-floating),
-#right-context-rail #street-level-panel:not(.panel-floating),
+#right-context-rail #cctv-panel,
+#right-context-rail #street-level-panel,
 #right-context-rail #weather-panel,
 #right-context-rail #recent-imagery-panel {
   width: 100%;
@@ -192,8 +192,8 @@
   flex-shrink: 1;
   min-height: 0;
 }
-#right-context-rail #cctv-panel.collapsed:not(.panel-floating),
-#right-context-rail #street-level-panel.collapsed:not(.panel-floating),
+#right-context-rail #cctv-panel.collapsed,
+#right-context-rail #street-level-panel.collapsed,
 #right-context-rail #weather-panel.collapsed,
 #right-context-rail #recent-imagery-panel.collapsed {
   width: var(--right-display-collapsed-width);
@@ -257,24 +257,19 @@
 #right-context-rail.layout-focus {
   height: var(--right-stack-max-height);
 }
-#right-context-rail.layout-exclusive
-  > [data-panel-id].collapsed:not(.panel-floating) {
+#right-context-rail.layout-exclusive > [data-panel-id].collapsed {
   display: none;
 }
-#right-context-rail.layout-focus
-  > [data-panel-id].collapsed:not(.panel-floating) {
+#right-context-rail.layout-focus > [data-panel-id].collapsed {
   display: block;
   flex: 0 0 auto;
 }
-#right-context-rail.layout-focus.layout-exclusive
-  > [data-panel-id].collapsed:not(.panel-floating) {
+#right-context-rail.layout-focus.layout-exclusive > [data-panel-id].collapsed {
   display: none;
 }
 #right-context-rail.layout-focus > #pp-toggles:not(.collapsed),
-#right-context-rail.layout-focus
-  > #cctv-panel:not(.collapsed):not(.panel-floating),
-#right-context-rail.layout-focus
-  > #street-level-panel:not(.collapsed):not(.panel-floating),
+#right-context-rail.layout-focus > #cctv-panel:not(.collapsed),
+#right-context-rail.layout-focus > #street-level-panel:not(.collapsed),
 #right-context-rail.layout-focus > #weather-panel:not(.collapsed),
 #right-context-rail.layout-focus > #recent-imagery-panel:not(.collapsed),
 #right-context-rail.layout-focus > #global-context-panel:not(.collapsed) {
@@ -293,10 +288,10 @@
   > #weather-panel:not(.collapsed)
   .weather-panel-inner,
 #right-context-rail.layout-focus
-  > #cctv-panel:not(.collapsed):not(.panel-floating)
+  > #cctv-panel:not(.collapsed)
   .cctv-panel-inner,
 #right-context-rail.layout-focus
-  > #street-level-panel:not(.collapsed):not(.panel-floating)
+  > #street-level-panel:not(.collapsed)
   .street-level-panel-inner,
 #right-context-rail.layout-focus
   > #recent-imagery-panel:not(.collapsed)