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/sidebar/ActivityItem.tsx

@@ -49,7 +49,7 @@ export function ActivityItem({
       className={cn(
         'flex w-full items-center gap-2 rounded-lg px-2.5 py-1.5 text-left transition-colors',
         'hover:bg-[rgba(255,255,255,0.03)]',
-        isRecent ? 'text-text-rail-label text-[0.72rem]' : 'text-[#e2e8f0] text-[0.8rem]'
+        isRecent ? 'text-text-rail-label text-[0.72rem]' : 'text-text-primary text-[0.8rem]'
       )}
       title={`${treeName}${ticketNumber ? ` (${ticketNumber})` : ''} — click to resume`}
       aria-label={