fix: resolve all biome warnings and formatting issues

- Remove unnecessary non-null assertions where values are guaranteed
- Replace array index access with .at() for safer element retrieval
- Use local variables to avoid repeated process.env lookups
- Replace any types with unknown in functional utilities
- Use nullish coalescing for TOTP hash byte access
- Auto-format security patches to match biome config

apps/cli/src/commands/setup.ts

@@ -219,9 +219,9 @@ async function setupRouter(): Promise<ShannonConfig> {
 
   const router: ShannonConfig['router'] = { default: defaultModel };
   if (routerProvider === 'openai') {
-    router!.openai_key = apiKey;
+    router.openai_key = apiKey;
   } else {
-    router!.openrouter_key = apiKey;
+    router.openrouter_key = apiKey;
   }
 
   return { router };