fix(network-maps): address design critique — harden, normalize, clarify, polish

- Archive: two-step inline confirm in card dropdown menu
- Delete Device/Edge: two-step inline confirm in PropertiesPanel footer
- Context menu Delete: floating confirm bar instead of immediate deletion
- AI Generate New: two-step confirm when replacing existing diagram nodes
- DiagramHeader: show 'Unsaved changes' in amber when isDirty and not saving
- deviceRegistry: SECURITY_COLOR #f97316 → #f87171 (deprecated ember orange removed)
- CanvasEmptyPrompt: remove backdrop-blur (design system violation)
- CanvasEmptyPrompt: remove redundant 'Skip AI' bottom button (duplicate of Build manually card)
- CanvasEmptyPrompt: rounded-xl/rounded-2xl → rounded-lg, border-2 → border
- Topology bar: h-1 → h-2 + native tooltip with category breakdown
- AIAssistPanel: replace pulse-dot loading with spinner (consistent with rest of feature)
- ContextMenu: add shadow-lg (consistent with other dropdowns)
- DeviceNode tooltip: Position.Bottom → Position.Top (avoids canvas-edge clipping)
- CanvasEmptyPrompt: raise ⌘↵ hint from /50 opacity to full text-muted-foreground

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/network/CanvasEmptyPrompt.tsx

@@ -63,7 +63,7 @@ export function CanvasEmptyPrompt({ onGenerate }: CanvasEmptyPromptProps) {
   if (mode === 'manual') {
     return (
       <div className="pointer-events-none absolute inset-x-0 bottom-6 z-10 flex justify-center px-6">
-        <div className="pointer-events-auto flex max-w-xl items-center gap-3 rounded-2xl border border-default bg-card/95 px-4 py-3 shadow-xl backdrop-blur">
+        <div className="pointer-events-auto flex max-w-xl items-center gap-3 rounded-lg border border-default bg-card px-4 py-3 shadow-xl">
           <div className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-accent/10 text-accent">
             <PencilRuler size={14} />
           </div>
@@ -94,7 +94,7 @@ export function CanvasEmptyPrompt({ onGenerate }: CanvasEmptyPromptProps) {
         }
       }}
     >
-      <div className="pointer-events-auto relative w-full max-w-lg rounded-xl border border-default bg-card p-8 shadow-2xl">
+      <div className="pointer-events-auto relative w-full max-w-lg rounded-lg border border-default bg-card p-8 shadow-2xl">
         <button
           onClick={switchToManual}
           disabled={loading}
@@ -123,7 +123,7 @@ export function CanvasEmptyPrompt({ onGenerate }: CanvasEmptyPromptProps) {
             <div className="grid gap-3 sm:grid-cols-2">
               <button
                 onClick={() => setMode('ai')}
-                className="rounded-xl border border-accent/40 bg-accent/10 p-4 text-left transition-colors hover:border-accent hover:bg-accent/15"
+                className="rounded-lg border border-accent/40 bg-accent/10 p-4 text-left transition-colors hover:border-accent hover:bg-accent/15"
               >
                 <div className="mb-3 inline-flex rounded-lg bg-accent/15 p-2 text-accent">
                   <Sparkles size={16} />
@@ -136,7 +136,7 @@ export function CanvasEmptyPrompt({ onGenerate }: CanvasEmptyPromptProps) {
 
               <button
                 onClick={switchToManual}
-                className="rounded-xl border-2 border-primary/20 bg-elevated/40 p-4 text-left transition-colors hover:border-accent hover:bg-elevated/60"
+                className="rounded-lg border border-default bg-elevated/40 p-4 text-left transition-colors hover:border-accent hover:bg-elevated/60"
               >
                 <div className="mb-3 inline-flex rounded-lg bg-primary/10 p-2 text-primary">
                   <PencilRuler size={16} />
@@ -148,13 +148,6 @@ export function CanvasEmptyPrompt({ onGenerate }: CanvasEmptyPromptProps) {
               </button>
             </div>
 
-            <button
-              onClick={switchToManual}
-              className="mt-4 flex w-full items-center justify-center gap-2 rounded-lg border border-default px-4 py-3 text-sm font-medium text-primary hover:border-accent hover:text-accent"
-            >
-              <PencilRuler size={14} />
-              Skip AI and start dragging devices
-            </button>
           </>
         ) : (
           <>
@@ -186,7 +179,7 @@ export function CanvasEmptyPrompt({ onGenerate }: CanvasEmptyPromptProps) {
                 autoFocus
                 className="w-full resize-none rounded-lg border border-default bg-input px-4 py-3 pb-7 text-sm text-primary placeholder:text-muted-foreground focus:border-accent focus:outline-none disabled:opacity-50"
               />
-              <span className="pointer-events-none absolute bottom-2 right-3 text-[10px] text-muted-foreground/50">
+              <span className="pointer-events-none absolute bottom-2 right-3 text-[10px] text-muted-foreground">
                 ⌘↵ to generate
               </span>
             </div>