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/pages/GuideDetailPage.tsx

@@ -46,7 +46,7 @@ export default function GuideDetailPage() {
             <p className="text-sm text-muted-foreground">{guide.summary}</p>
           </div>
         </div>
-        <div className="flex items-center gap-4 mt-4 pt-4 border-t" style={{ borderColor: 'var(--glass-border)' }}>
+        <div className="flex items-center gap-4 mt-4 pt-4 border-t" style={{ borderColor: 'var(--color-border-default)' }}>
           <span className="font-sans text-xs text-[0.625rem] uppercase tracking-widest text-muted-foreground">
             {guide.sections.length} {guide.sections.length === 1 ? 'section' : 'sections'}
           </span>