FRE-622: Wire analytics services to tRPC API layer with comprehensive router

Create analytics-router.ts with ~30 tRPC endpoints for KPI management, alert
rules, scheduled reports, cohort analysis, and NPS survey integration.
Register router in index.ts under 'analytics' namespace. Fix pre-existing
bugs in service files: snake_case to camelCase conversion, missing non-null
assertions, and incorrect DB access patterns.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/lib/analytics/cohort-analysis.ts

@@ -40,7 +40,7 @@ export async function createCohort(
   };
 
   const result = await db.insert(cohorts).values(cohort).returning();
-  return result[0];
+  return result[0]!;
 }
 
 export async function addCohortMember(
@@ -103,7 +103,7 @@ export async function getCohortAnalysis(
   };
 
   return {
-    cohort,
+    cohort: cohort!,
     retention,
     metrics,
   };

src/lib/analytics/nps-service.ts

@@ -42,7 +42,7 @@ export async function submitNPSResponse(
   };
 
   const result = await db.insert(npsResponses).values(response).returning();
-  return result[0];
+  return result[0]!;
 }
 
 export async function calculateNPS(
@@ -122,7 +122,7 @@ export async function getNPSOverTime(
   const grouped: Record<string, NPSResponse[]> = {};
 
   for (const response of responses) {
-    const date = response.created_at;
+    const date = response.createdAt;
     const key =
       granularity === "weekly"
         ? getWeekKey(date)
@@ -186,7 +186,7 @@ export function generateNPSSurveyInAppPrompt(): { question: string; scale: strin
 function getWeekKey(date: Date): string {
   const start = new Date(date);
   start.setDate(start.getDate() - start.getDay());
-  return start.toISOString().split("T")[0];
+  return start.toISOString().split("T")[0]!;
 }
 
 function getMonthKey(date: Date): string {

src/lib/analytics/report-generator.ts

@@ -178,7 +178,7 @@ export async function createScheduledReport(
     lastRunAt: null,
     nextRunAt: computeNextRun(input.schedule),
   }).returning();
-  return result[0];
+  return result[0]!;
 }
 
 export async function getActiveScheduledReports(

src/lib/analytics/slack-alerts.ts

@@ -134,7 +134,7 @@ export async function sendSlackAlert(
       type: "header",
       text: {
         type: "plain_text",
-        text: `🚨 KPI Alert: ${alert.kpi_key}`,
+        text: `🚨 KPI Alert: ${alert.kpiKey}`,
         emoji: true,
       },
     },
@@ -147,7 +147,7 @@ export async function sendSlackAlert(
         },
         {
           type: "mrkdwn",
-          text: `*Current Value:*\n${alert.kpi_value.toFixed(2)}`,
+          text: `*Current Value:*\n${alert.kpiValue.toFixed(2)}`,
         },
         {
           type: "mrkdwn",
@@ -155,7 +155,7 @@ export async function sendSlackAlert(
         },
         {
           type: "mrkdwn",
-          text: `*Time:*\n${new Date(alert.created_at?.getTime() ?? Date.now()).toISOString()}`,
+          text: `*Time:*\n${new Date(alert.createdAt.getTime()).toISOString()}`,
         },
       ],
     },
@@ -196,22 +196,14 @@ export async function sendSlackAlert(
 }
 
 async function markAlertSent(alertId: number): Promise<void> {
-  const db = await getDb();
-  if (db) {
+  try {
+    const { db } = await import("../../db/config/migrations");
     await db
       .update(alerts)
       .set({ wasSent: true, sentAt: new Date() })
       .where(eq(alerts.id, alertId));
-  }
-}
-
-async function getDb(): Promise<DrizzleDB | undefined> {
-  try {
-    const { createDatabaseManager } = await import("../../db/config/database");
-    const manager = createDatabaseManager();
-    return manager.getDb();
   } catch {
-    return undefined;
+    console.error("Failed to mark alert as sent:", alertId);
   }
 }