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/applicationShell.js

@@ -105,7 +105,6 @@ export class StyleManager extends ShellFacade {
         _setRadioDisclosure: (...args) => this._setRadioDisclosure(...args),
         _syncCctvPanelViewport: (...args) =>
           this._syncCctvPanelViewport(...args),
-        _onPanelResized: (...args) => this._onPanelResized(...args),
         _syncContextRadioLauncherState: (...args) =>
           this._syncContextRadioLauncherState(...args),
         _showToast: (...args) => this._showToast(...args),
@@ -960,7 +959,6 @@ export class StyleManager extends ShellFacade {
           this._dataManager?.setLayerParams('street-level', params, options),
         setPanelCollapsed: (collapsed, options) =>
           this.setPanelCollapsed('street-level-panel', collapsed, options),
-        dockPanel: () => this._panelChrome.dockPanel('street-level-panel'),
         showToast: (message) => this._showToast(message),
         // Lets the panel open for a user, voice or tool switch-on, not a restore.
         subscribeEnableRequests: (listener) =>
@@ -1516,13 +1514,6 @@ export class StyleManager extends ShellFacade {
     this._initCockpitDisplayPortal();
   }
 
-  /** A portable panel was resized or docked: refit any viewport inside it. */
-  _onPanelResized(panelId) {
-    if (panelId === 'cctv-panel') this._syncCctvPanelViewport();
-    if (panelId === 'street-level-panel')
-      this._streetLevelControls?.onPanelResized();
-  }
-
   /**
    * Recalculates the CCTV panel max-height based on its current top position
    * and the window height, enabling internal scroll without viewport overflow.