pagedraw: replace hardcoded chrome colors with semantic tokens

Implements the P0 color item from the PageDraw design review. Swap raw
hex/palette chrome colors for the semantic tokens shared by both lib
hosts (artcraft desktop + artcraft-webapp):

- ContextMenu: #1A1A1A/#333333/#ECECEC -> bg-ui-panel, white/10 hairlines,
  text-base-fg/90
- SideToolbar: zinc swatch + #404040/#303030 popovers -> ui-controls /
  bg-ui-panel + white/10 borders
- SliderWithIndicator: #5F5F68 tooltip -> bg-ui-controls
- SplitPane: gray-500/600 -> white/20-30
- HistoryStack: text-gray-400 -> text-base-fg/50
- PageDraw + base-image-selector: blue-500/600 accents -> primary token
  (so the editor accent matches the product's brand-primary)
- pagedraw.css pegboard: #1b1b1b -> var(--st-canvas, #1b1b1b)

Only tokens defined in both host themes are used. Konva canvas-paint
colors (node strokes, brush defaults, selection fills) are intentionally
left as literals — they're canvas content, not CSS chrome. Oversized
modules deferred per scope.

frontend/apps/artcraft-webapp/src/pages/pagedraw/base-image-selector.tsx

@@ -148,8 +148,8 @@ export function BaseImageSelector({
         onDrop={onDrop}
         className={`flex h-full w-full cursor-pointer flex-col items-center justify-center gap-4 rounded-2xl border-2 border-dashed p-8 text-center transition-colors ${
           isDragging
-            ? "border-blue-400 bg-blue-500/10"
-            : "border-ui-panel-border bg-ui-background hover:border-blue-400/50"
+            ? "border-primary-400 bg-primary/10"
+            : "border-ui-panel-border bg-ui-background hover:border-primary-400/50"
         } ${busy ? "pointer-events-none opacity-60" : ""}`}
       >
         <input
@@ -159,7 +159,7 @@ export function BaseImageSelector({
           onChange={onFileInput}
           disabled={busy}
         />
-        <div className="flex h-14 w-14 items-center justify-center rounded-2xl border border-blue-400/30 bg-blue-500/30 text-blue-300">
+        <div className="flex h-14 w-14 items-center justify-center rounded-2xl border border-primary-400/30 bg-primary/30 text-primary-300">
           <FontAwesomeIcon
             icon={busy ? faSpinnerThird : faPencil}
             className={`text-xl ${busy ? "animate-spin" : ""}`}

frontend/libs/components/pagedraw/src/lib/HistoryStack.tsx

@@ -170,7 +170,7 @@ export const HistoryStack = ({
         <div className="mb-2 flex w-full items-center justify-center">
           <FontAwesomeIcon
             icon={faClockRotateLeft}
-            className="p-1 text-gray-400"
+            className="p-1 text-base-fg/50"
           />
         </div>
         <div

frontend/libs/components/pagedraw/src/lib/PageDraw.tsx

@@ -154,7 +154,7 @@ const Edit3DButton = memo(function Edit3DButton({
 
   return (
     <button
-      className="pointer-events-auto fixed z-40 -translate-x-1/2 -translate-y-1/2 rounded-full bg-blue-600 px-3 py-1 text-xs font-semibold text-white shadow-lg hover:bg-blue-500"
+      className="pointer-events-auto fixed z-40 -translate-x-1/2 -translate-y-1/2 rounded-full bg-primary px-3 py-1 text-xs font-semibold text-white shadow-lg hover:bg-primary-400"
       style={{ left: btnLeft, top: btnTop }}
       onPointerDown={(e) => e.stopPropagation()}
       onClick={() => onEdit(nodeId)}
@@ -185,7 +185,7 @@ function DragScrubButton({
   return (
     <button
       title={title}
-      className="flex h-10 w-10 cursor-move items-center justify-center rounded-full bg-black/70 text-white shadow-lg hover:bg-black/90 active:bg-blue-600"
+      className="flex h-10 w-10 cursor-move items-center justify-center rounded-full bg-black/70 text-white shadow-lg hover:bg-black/90 active:bg-primary"
       onPointerDown={onPointerDown}
       onPointerMove={onPointerMove}
     >
@@ -254,7 +254,7 @@ const Edit3DScrubControls = memo(function Edit3DScrubControls({
       />
       <button
         onClick={() => overlayHandle.current?.commit()}
-        className="flex h-10 w-10 items-center justify-center rounded-full bg-blue-600 text-sm font-bold text-white shadow-lg hover:bg-blue-500"
+        className="flex h-10 w-10 items-center justify-center rounded-full bg-primary text-sm font-bold text-white shadow-lg hover:bg-primary-400"
         onPointerDown={(e) => e.stopPropagation()}
       >
         ✓

frontend/libs/components/pagedraw/src/lib/components/ui/ContextMenu.tsx

@@ -41,7 +41,7 @@ export const ContextMenu: React.FC<ContextMenuProps> = ({ items, onAction, onClo
         left: `${position.x}px`,
         top: `${position.y}px`,
       }}
-      className="fixed z-[9999999] min-w-[220px] bg-[#1A1A1A] rounded-lg shadow-xl border border-[#333333] py-1 select-none"
+      className="fixed z-[9999999] min-w-[220px] bg-ui-panel rounded-lg shadow-xl border border-white/10 py-1 select-none"
     >
       {items.map((item, index) => (
         <React.Fragment key={index}>
@@ -50,14 +50,14 @@ export const ContextMenu: React.FC<ContextMenuProps> = ({ items, onAction, onClo
               onAction(item.action);  // Pass the action identifier up
               onClose();
             }}
-            className="w-full px-4 py-2.5 flex items-center gap-3 hover:bg-[#333333] text-[#ECECEC] text-[13px] transition-colors duration-75 ease-in-out"
+            className="w-full px-4 py-2.5 flex items-center gap-3 hover:bg-white/10 text-base-fg/90 text-[13px] transition-colors duration-75 ease-in-out"
           >
-            <span className="w-5 h-5 flex items-center justify-center text-[#ECECEC]">
+            <span className="w-5 h-5 flex items-center justify-center text-base-fg/90">
               {item.icon}
             </span>
             <span className="font-normal">{item.label}</span>
           </button>
-          {item.divider && <div className="h-[1px] bg-[#333333] mx-2 my-1" />}
+          {item.divider && <div className="h-[1px] bg-white/10 mx-2 my-1" />}
         </React.Fragment>
       ))}
     </div>,

frontend/libs/components/pagedraw/src/lib/components/ui/SideToolbar.tsx

@@ -170,7 +170,7 @@ const SideToolbar: React.FC<SideToolbarProps> = ({
     extra?: React.ReactNode,
   ) => (
     <div className={`glass relative w-fit rounded-2xl p-4 shadow-lg`}>
-      <button className="bg-zinc-700 text-zinc-300 hover:bg-zinc-600 absolute left-4 top-4 flex h-8 w-8 items-center justify-center rounded-full">
+      <button className="bg-ui-controls/60 text-base-fg hover:bg-ui-controls/80 absolute left-4 top-4 flex h-8 w-8 items-center justify-center rounded-full">
         <FontAwesomeIcon icon={faEyeDropper} size="sm" />
       </button>
 
@@ -378,7 +378,7 @@ const SideToolbar: React.FC<SideToolbarProps> = ({
             {open === "shape-color" && (
               <div
                 onMouseLeave={() => setOpen(null)}
-                className="absolute left-14 top-1/2 -translate-y-1/2 rounded-xl border border-[#404040] bg-[#303030] transition-all duration-200 ease-in-out"
+                className="absolute left-14 top-1/2 -translate-y-1/2 rounded-xl border border-white/10 bg-ui-panel transition-all duration-200 ease-in-out"
               >
                 {ShapePopout}
               </div>
@@ -547,7 +547,7 @@ const SideToolbar: React.FC<SideToolbarProps> = ({
                 onMouseLeave={() => {
                   setOpen(null);
                 }}
-                className="absolute left-14 top-1/2 -translate-y-1/2 rounded-xl border border-[#404040] bg-[#303030] transition-all duration-200 ease-in-out"
+                className="absolute left-14 top-1/2 -translate-y-1/2 rounded-xl border border-white/10 bg-ui-panel transition-all duration-200 ease-in-out"
               >
                 {popout}
               </div>

frontend/libs/components/pagedraw/src/lib/components/ui/SliderWithIndicator.tsx

@@ -58,7 +58,7 @@ const SliderWithIndicator: React.FC<SliderWithIndicatorProps> = ({
               absolute
               top-6 -translate-x-1/2
               transform rounded
-              bg-[#5F5F68]
+              bg-ui-controls
               px-2 py-1
               text-xs font-medium
               text-white shadow-lg

frontend/libs/components/pagedraw/src/lib/components/ui/SplitPane.tsx

@@ -81,8 +81,8 @@ export default function SplitPane({
       </div>
 
       <div
-        className="w-1 cursor-col-resize select-none bg-gray-500/80
-                   transition hover:bg-gray-600"
+        className="w-1 cursor-col-resize select-none bg-white/20
+                   transition hover:bg-white/30"
         onMouseDown={beginDrag}
         onTouchStart={beginDrag}
       />

frontend/libs/components/pagedraw/src/lib/pagedraw.css

@@ -3,7 +3,9 @@
 .pegboard-bg {
   inset: 0;
   z-index: 0;
-  background-color: #1b1b1b;
+  /* Themeable canvas backdrop; hosts may set --st-canvas, otherwise the
+     original dark grey is used. */
+  background-color: var(--st-canvas, #1b1b1b);
   background-size: 50px 50px;
   background-position:
     0 0,