style: auto-fix ESLint issues (curly braces and formatting)

- Add curly braces to all if/else/for/while statements
- Fix indentation and trailing spaces
- Auto-fixed 372 linting errors using eslint --fix
- Remaining issues are warnings only (non-null assertions, explicit any types)

src/gateway/auth.ts

@@ -80,7 +80,7 @@ function extractQueryToken(req: IncomingMessage): string | undefined {
 }
 
 function extractTailscaleIdentity(req: IncomingMessage, config: AuthConfig): string | undefined {
-  if (!config.tailscaleIdentity) return undefined;
+  if (!config.tailscaleIdentity) {return undefined;}
   const header = req.headers['tailscale-user-login'];
   if (typeof header === 'string' && header.length > 0) {
     return header;