fix: eliminate deprecated cyan, glass-border, and off-palette colors site-wide

- Replace all rgba(6,182,212,...) cyan focus borders and accents with
  rgba(249,115,22,...) ember orange across 21+ component files
- Remove all var(--glass-border) references (undefined variable) with
  var(--color-border-default) across 24 files
- Remove deprecated blur orbs and glass-morphism effects from
  SurveyPage, SurveyThankYouPage, and LoginPage
- Migrate landing.css from hardcoded hex to CSS custom properties
  (~97 replacements for single-source theming)
- Fix off-palette grays in FlowPilotAnalyticsPage chart styling
  (#8891a0 → #848b9b, #18191f → var(--color-bg-card))
- Update stale comments: "cyan brand" → "accent brand" in GlowEdge,
  "gradient cyan square" → "gradient orange square" in BrandLogo
- Rename glow-cyan SVG filter ID to glow-accent
- Fix category color comment: "cyan" → "deep orange"

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/copilot/CopilotPanel.tsx

@@ -96,13 +96,13 @@ export function CopilotPanel({ isOpen, onClose, treeId, sessionId, currentNodeId
         background: 'rgba(16, 17, 20, 0.95)',
         backdropFilter: 'var(--glass-blur)',
         WebkitBackdropFilter: 'var(--glass-blur)',
-        borderColor: 'var(--glass-border)',
+        borderColor: 'var(--color-border-default)',
       }}
     >
       {/* Header */}
       <div
         className="flex items-center justify-between px-4 py-3 border-b shrink-0"
-        style={{ borderColor: 'var(--glass-border)' }}
+        style={{ borderColor: 'var(--color-border-default)' }}
       >
         <div className="flex items-center gap-2">
           <Sparkles size={16} className="text-primary" />
@@ -155,7 +155,7 @@ export function CopilotPanel({ isOpen, onClose, treeId, sessionId, currentNodeId
       </div>
 
       {/* Input */}
-      <div className="px-4 py-3 border-t shrink-0" style={{ borderColor: 'var(--glass-border)' }}>
+      <div className="px-4 py-3 border-t shrink-0" style={{ borderColor: 'var(--color-border-default)' }}>
         <div className="flex items-end gap-2">
           <textarea
             ref={inputRef}
@@ -165,7 +165,7 @@ export function CopilotPanel({ isOpen, onClose, treeId, sessionId, currentNodeId
             placeholder="Ask about this step..."
             rows={1}
             className="flex-1 resize-none rounded-xl border bg-card text-foreground text-[0.8125rem] placeholder:text-muted-foreground px-3.5 py-2.5 focus:outline-hidden focus:border-primary/30"
-            style={{ borderColor: 'var(--glass-border)' }}
+            style={{ borderColor: 'var(--color-border-default)' }}
             disabled={loading || initializing}
           />
           <button