fix: add periodic flush and graceful shutdown for server-side telemetry

The TelemetryClient only flushed at 50 events, so the server silently
lost all queued telemetry on restart. Add startPeriodicFlush/stop methods
to TelemetryClient, wire up 60s periodic flush in server initTelemetry,
and flush on SIGTERM/SIGINT before exit.

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

server/src/index.ts

@@ -39,7 +39,7 @@ import { createStorageServiceFromConfig } from "./storage/index.js";
 import { printStartupBanner } from "./startup-banner.js";
 import { getBoardClaimWarningUrl, initializeBoardClaimChallenge } from "./board-claim.js";
 import { maybePersistWorktreeRuntimePorts } from "./worktree-config.js";
-import { initTelemetry } from "./telemetry.js";
+import { initTelemetry, getTelemetryClient } from "./telemetry.js";
 
 type BetterAuthSessionUser = {
   id: string;
@@ -728,18 +728,26 @@ export async function startServer(): Promise<StartedServer> {
     });
   });
   
-  if (embeddedPostgres && embeddedPostgresStartedByThisProcess) {
+  {
     const shutdown = async (signal: "SIGINT" | "SIGTERM") => {
-      logger.info({ signal }, "Stopping embedded PostgreSQL");
-      try {
-        await embeddedPostgres?.stop();
-      } catch (err) {
-        logger.error({ err }, "Failed to stop embedded PostgreSQL cleanly");
-      } finally {
-        process.exit(0);
+      const telemetryClient = getTelemetryClient();
+      if (telemetryClient) {
+        telemetryClient.stop();
+        await telemetryClient.flush();
       }
+
+      if (embeddedPostgres && embeddedPostgresStartedByThisProcess) {
+        logger.info({ signal }, "Stopping embedded PostgreSQL");
+        try {
+          await embeddedPostgres?.stop();
+        } catch (err) {
+          logger.error({ err }, "Failed to stop embedded PostgreSQL cleanly");
+        }
+      }
+
+      process.exit(0);
     };
-  
+
     process.once("SIGINT", () => {
       void shutdown("SIGINT");
     });