fix: frontend consistency audit — 55 files cleaned up

Consistency fixes:
- Extract getThisWeekRange/getThisMonthRange to shared lib/utils/dateRanges.ts
  (removed 4 identical copy-pasted definitions)
- Add error boundaries for behavior, cdn, search, pagespeed pages
  (4 new error.tsx files — previously fell through to generic parent error)
- Add "View setup guide" CTA to empty states on journeys and behavior pages
  (previously showed text with no actionable button)
- Fix non-lazy useState initializer in funnel detail page
- Fix Bot & Spam settings header from text-xl to text-2xl (matches all other sections)
- Add useMinimumLoading to PageSpeed skeleton (consistent with all other pages)

Cleanup:
- Remove 438 redundant dark: class prefixes (app is dark-mode only)
  text-neutral-500 dark:text-neutral-400 → text-neutral-400 (206 occurrences)
  text-neutral-900 dark:text-white → text-white (232 occurrences)
- Remove dead @stripe/react-stripe-js and @stripe/stripe-js packages
  (billing migrated to Polar, no code imports Stripe)
- Remove duplicate motion package (framer-motion is the one actually used)

components/funnels/BreakdownDrawer.tsx

@@ -50,7 +50,7 @@ export default function BreakdownDrawer({ siteId, funnelId, stepIndex, stepName,
         {/* Header */}
         <div className="flex items-center justify-between px-6 py-4 border-b border-neutral-200 dark:border-neutral-800">
           <div>
-            <h3 className="font-semibold text-neutral-900 dark:text-white">Step Breakdown</h3>
+            <h3 className="font-semibold text-white">Step Breakdown</h3>
             <p className="text-sm text-neutral-500">{stepName}</p>
           </div>
           <button onClick={onClose} className="p-2 text-neutral-400 hover:text-neutral-600 rounded-lg">
@@ -91,7 +91,7 @@ export default function BreakdownDrawer({ siteId, funnelId, stepIndex, stepName,
             <div className="space-y-2">
               {breakdown.entries.map(entry => (
                 <div key={entry.value} className="flex items-center justify-between py-2 px-3 rounded-lg hover:bg-neutral-50 dark:hover:bg-neutral-800/50">
-                  <span className="text-sm text-neutral-900 dark:text-white truncate mr-4">
+                  <span className="text-sm text-white truncate mr-4">
                     {entry.value || '(unknown)'}
                   </span>
                   <div className="flex items-center gap-4 text-sm shrink-0">

components/funnels/FunnelForm.tsx

@@ -206,7 +206,7 @@ export default function FunnelForm({ siteId, initialData, onSubmit, submitLabel,
           Back to Funnels
         </Link>
 
-        <h1 className="text-2xl font-bold text-neutral-900 dark:text-white mb-2">
+        <h1 className="text-2xl font-bold text-white mb-2">
           {initialData ? 'Edit Funnel' : 'Create New Funnel'}
         </h1>
         <p className="text-neutral-600 dark:text-neutral-400">
@@ -252,7 +252,7 @@ export default function FunnelForm({ siteId, initialData, onSubmit, submitLabel,
         {/* Steps */}
         <div className="space-y-4 mb-6">
           <div className="flex items-center justify-between">
-            <h3 className="text-lg font-semibold text-neutral-900 dark:text-white">
+            <h3 className="text-lg font-semibold text-white">
               Funnel Steps
             </h3>
           </div>