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/tree-editor/GlowEdge.tsx

@@ -52,7 +52,7 @@ export function GlowEdgeDefs() {
           <stop offset="100%" stopColor="rgba(255,255,255,0.08)" />
         </linearGradient>
 
-        {/* Downstream: cyan brand */}
+        {/* Downstream: accent brand */}
         <linearGradient id="edge-gradient-downstream" x1="0%" y1="0%" x2="0%" y2="100%">
           <stop offset="0%" stopColor="#ea580c" />
           <stop offset="100%" stopColor="#f97316" />
@@ -72,7 +72,7 @@ export function GlowEdgeDefs() {
             <feMergeNode in="SourceGraphic" />
           </feMerge>
         </filter>
-        <filter id="glow-cyan" x="-30%" y="-30%" width="160%" height="160%">
+        <filter id="glow-accent" x="-30%" y="-30%" width="160%" height="160%">
           <feGaussianBlur in="SourceGraphic" stdDeviation="3" result="blur" />
           <feMerge>
             <feMergeNode in="blur" />
@@ -120,7 +120,7 @@ function GlowEdgeComponent({
 
   const filterId = edgeState === 'default' ? 'glow-default'
     : edgeState === 'upstream' ? 'glow-amber'
-    : 'glow-cyan'
+    : 'glow-accent'
 
   return (
     <>