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/dashboard/TopReferrers.tsx

@@ -97,7 +97,7 @@ export default function TopReferrers({ referrers, collectReferrers = true, siteI
         <div className="flex items-center justify-between mb-4">
           <div className="flex items-center gap-2">
             <ArrowSquareOut className="w-5 h-5 text-neutral-400 dark:text-neutral-500" weight="bold" />
-            <h3 className="text-lg font-semibold text-neutral-900 dark:text-white">
+            <h3 className="text-lg font-semibold text-white">
               Referrers
             </h3>
             {showViewAll && (
@@ -115,7 +115,7 @@ export default function TopReferrers({ referrers, collectReferrers = true, siteI
         <div className="space-y-2 flex-1 min-h-[270px]">
           {!collectReferrers ? (
             <div className="h-full flex flex-col items-center justify-center text-center px-4">
-              <p className="text-neutral-500 dark:text-neutral-400 text-sm">Referrer tracking is disabled in site settings</p>
+              <p className="text-neutral-400 text-sm">Referrer tracking is disabled in site settings</p>
             </div>
           ) : hasData ? (
             <>
@@ -132,7 +132,7 @@ export default function TopReferrers({ referrers, collectReferrers = true, siteI
                       className="absolute inset-y-0.5 left-0.5 bg-brand-orange/15 dark:bg-brand-orange/40 rounded-md transition-all"
                       style={{ width: `${barWidth}%` }}
                     />
-                    <div className="relative flex-1 truncate text-neutral-900 dark:text-white flex items-center gap-3">
+                    <div className="relative flex-1 truncate text-white flex items-center gap-3">
                       {renderReferrerIcon(ref.referrer)}
                       <span className="truncate" title={ref.referrer}>{getReferrerDisplayName(ref.referrer)}</span>
                     </div>
@@ -154,12 +154,12 @@ export default function TopReferrers({ referrers, collectReferrers = true, siteI
           ) : (
             <div className="h-full flex flex-col items-center justify-center text-center px-6 py-8 gap-3">
               <div className="rounded-full bg-neutral-100 dark:bg-neutral-800 p-4">
-                <GlobeIcon className="w-8 h-8 text-neutral-500 dark:text-neutral-400" />
+                <GlobeIcon className="w-8 h-8 text-neutral-400" />
               </div>
-              <h4 className="font-semibold text-neutral-900 dark:text-white">
+              <h4 className="font-semibold text-white">
                 No referrers yet
               </h4>
-              <p className="text-sm text-neutral-500 dark:text-neutral-400 max-w-xs">
+              <p className="text-sm text-neutral-400 max-w-xs">
                 Traffic sources will appear here when visitors come from external sites.
               </p>
               <Link
@@ -186,7 +186,7 @@ export default function TopReferrers({ referrers, collectReferrers = true, siteI
             value={modalSearch}
             onChange={(e) => setModalSearch(e.target.value)}
             placeholder="Search referrers..."
-            className="w-full px-3 py-2 mb-3 text-sm bg-neutral-50 dark:bg-neutral-800 border border-neutral-200 dark:border-neutral-700 rounded-lg text-neutral-900 dark:text-white placeholder-neutral-400 dark:placeholder-neutral-500 focus:outline-none focus:ring-2 focus:ring-brand-orange/50"
+            className="w-full px-3 py-2 mb-3 text-sm bg-neutral-50 dark:bg-neutral-800 border border-neutral-200 dark:border-neutral-700 rounded-lg text-white placeholder-neutral-400 dark:placeholder-neutral-500 focus:outline-none focus:ring-2 focus:ring-brand-orange/50"
           />
         </div>
         <div className="max-h-[80vh]">
@@ -208,7 +208,7 @@ export default function TopReferrers({ referrers, collectReferrers = true, siteI
                     onClick={() => { if (onFilter) { onFilter({ dimension: 'referrer', operator: 'is', values: [ref.referrer] }); setIsModalOpen(false) } }}
                     className={`flex items-center justify-between h-9 group hover:bg-neutral-50 dark:hover:bg-neutral-800 rounded-lg px-2 transition-colors${onFilter ? ' cursor-pointer' : ''}`}
                   >
-                    <div className="flex-1 truncate text-neutral-900 dark:text-white flex items-center gap-3">
+                    <div className="flex-1 truncate text-white flex items-center gap-3">
                       {renderReferrerIcon(ref.referrer)}
                       <span className="truncate" title={ref.referrer}>{getReferrerDisplayName(ref.referrer)}</span>
                     </div>