fix(api,web): env startup validation, QueryClient defaults, warn on missing REDIS_URL

- Throw at startup in production if REDIS_URL/DATABASE_URL/NEXTAUTH_SECRET missing
- Warn in development when REDIS_URL falls back to localhost
- QueryClient: add gcTime, disable refetchOnWindowFocus, skip retry on 4xx

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

apps/web/src/instrumentation.ts

@@ -1,4 +1,11 @@
 export async function register() {
+  // Validate required env vars at startup — throws immediately in production
+  // if REDIS_URL, DATABASE_URL, or NEXTAUTH_SECRET are missing.
+  if (process.env.NEXT_RUNTIME === "nodejs") {
+    const { assertProductionEnv } = await import("@capakraken/api");
+    assertProductionEnv();
+  }
+
   // Only load Sentry in production — the worker.js crash in dev mode
   // (vendor-chunks/lib/worker.js MODULE_NOT_FOUND) makes the dev server unstable
   if (process.env.NODE_ENV === "production") {

apps/web/src/lib/trpc/provider.tsx

@@ -50,12 +50,18 @@ export function TRPCProvider({ children }: { children: React.ReactNode }) {
         defaultOptions: {
           queries: {
             staleTime: 60_000, // 60 seconds — reduces refetches on navigation
+            gcTime: 5 * 60_000, // 5 minutes — keep inactive queries in memory
             refetchOnWindowFocus: false,
             refetchOnReconnect: false,
             retry: (failureCount, error) => {
               // Never retry UNAUTHORIZED — redirect immediately instead
               if (isUnauthorizedTrpcError(error)) return false;
-              return failureCount < 1;
+              // Don't retry on 4xx errors (auth, not found, bad input)
+              if (error instanceof TRPCClientError) {
+                const code = error.data?.httpStatus as number | undefined;
+                if (code !== undefined && code >= 400 && code < 500) return false;
+              }
+              return failureCount < 2;
             },
           },
         },