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/controls.css

@@ -103,115 +103,6 @@
   opacity: 0.96;
 }
 
-/* ── Portable rail panels ────────────────────
-   Rail placement in layers.css is guarded with :not(.panel-floating), so
-   these rules only have to beat a panel's base placement (one id). */
-.panel-portable .panel-header {
-  cursor: grab;
-}
-.panel-portable.panel-dragging .panel-header {
-  cursor: grabbing;
-}
-#right-context-rail > .panel-floating {
-  position: fixed;
-  inset: auto;
-  /* Above every docked rail panel; keep in step with PANEL_Z_FLOATING_FLOOR. */
-  z-index: 111;
-  max-height: calc(100vh - 12px);
-  margin: 0;
-  flex: none;
-  pointer-events: auto;
-}
-/* A collapsed window shows only its header strip; its inline height stays. */
-#right-context-rail > .panel-floating.collapsed {
-  max-height: max-content;
-}
-.panel-floating[style*='height'] > .cctv-panel-inner {
-  box-sizing: border-box;
-  height: 100%;
-  max-height: none;
-}
-.panel-resize-edge,
-.panel-resize-grip {
-  position: absolute;
-  z-index: 3;
-  touch-action: none;
-}
-.panel-resize-edge[data-dir='n'],
-.panel-resize-edge[data-dir='s'] {
-  left: 10px;
-  right: 10px;
-  height: 7px;
-  cursor: ns-resize;
-}
-.panel-resize-edge[data-dir='n'] {
-  top: -3px;
-}
-.panel-resize-edge[data-dir='s'] {
-  bottom: -3px;
-}
-.panel-resize-edge[data-dir='e'],
-.panel-resize-edge[data-dir='w'] {
-  top: 10px;
-  bottom: 10px;
-  width: 7px;
-  cursor: ew-resize;
-}
-.panel-resize-edge[data-dir='e'] {
-  right: -3px;
-}
-.panel-resize-edge[data-dir='w'] {
-  left: -3px;
-}
-.panel-resize-edge[data-dir='ne'],
-.panel-resize-edge[data-dir='nw'],
-.panel-resize-edge[data-dir='sw'] {
-  width: 14px;
-  height: 14px;
-}
-.panel-resize-edge[data-dir='ne'] {
-  top: -3px;
-  right: -3px;
-  cursor: nesw-resize;
-}
-.panel-resize-edge[data-dir='nw'] {
-  top: -3px;
-  left: -3px;
-  cursor: nwse-resize;
-}
-.panel-resize-edge[data-dir='sw'] {
-  bottom: -3px;
-  left: -3px;
-  cursor: nesw-resize;
-}
-.panel-resize-grip {
-  right: 3px;
-  bottom: 3px;
-  width: 14px;
-  height: 14px;
-  cursor: nwse-resize;
-  opacity: 0.55;
-  clip-path: polygon(100% 0, 100% 100%, 0 100%);
-  background: repeating-linear-gradient(
-    135deg,
-    transparent 0 3px,
-    rgba(0, 212, 255, 0.6) 3px 4px
-  );
-  transition: opacity var(--transition-fast);
-}
-.panel-portable:hover .panel-resize-grip,
-.panel-resizing .panel-resize-grip {
-  opacity: 1;
-}
-.panel-collapsible.collapsed > .panel-resize-edge,
-.panel-collapsible.collapsed > .panel-resize-grip {
-  display: none;
-}
-.panel-resizing,
-.panel-resizing * {
-  user-select: none;
-}
-
 .panel-title {
   font-family: var(--font-mono);
   font-size: 9px;