Add Web Vitals performance tracking (LCP, INP, CLS, FCP, TTFB)

End-to-end performance metrics tracking: dedicated database table with
percentile aggregation, tracker collection behind data-perf attribute,
/api/send handling, report API endpoints, and Performance dashboard page
with threshold-based metric cards, time-series chart, and per-page breakdown.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/constants.ts

@@ -98,6 +98,15 @@ export const FILTER_COLUMNS = {
 export const COLLECTION_TYPE = {
   event: 'event',
   identify: 'identify',
+  performance: 'performance',
+} as const;
+
+export const WEB_VITALS_THRESHOLDS = {
+  lcp: { good: 2500, poor: 4000, unit: 'ms' },
+  inp: { good: 200, poor: 500, unit: 'ms' },
+  cls: { good: 0.1, poor: 0.25, unit: '' },
+  fcp: { good: 1800, poor: 3000, unit: 'ms' },
+  ttfb: { good: 800, poor: 1800, unit: 'ms' },
 } as const;
 
 export const EVENT_TYPE = {

src/lib/schema.ts

@@ -112,6 +112,7 @@ export const reportTypeParam = z.enum([
   'funnel',
   'goal',
   'journey',
+  'performance',
   'retention',
   'revenue',
   'utm',
@@ -200,6 +201,17 @@ export const utmReportSchema = z.object({
   }),
 });
 
+export const performanceReportSchema = z.object({
+  type: z.literal('performance'),
+  parameters: z.object({
+    startDate: z.coerce.date(),
+    endDate: z.coerce.date(),
+    unit: unitParam.optional(),
+    timezone: timezoneParam.optional(),
+    metric: z.enum(['lcp', 'inp', 'cls', 'fcp', 'ttfb']).optional(),
+  }),
+});
+
 export const revenueReportSchema = z.object({
   type: z.literal('revenue'),
   parameters: z.object({
@@ -244,6 +256,7 @@ export const reportTypeSchema = z.discriminatedUnion('type', [
   goalReportSchema,
   funnelReportSchema,
   journeyReportSchema,
+  performanceReportSchema,
   retentionReportSchema,
   utmReportSchema,
   revenueReportSchema,