feat(pagination): add pagination utility functions for handling page size and continuation tokens

- Introduced `PaginationRequest` interface to define pagination parameters.
- Implemented `parsePagination` function to extract and validate pagination parameters from a URL.
- Added `encodeContinuationToken` and `decodeContinuationToken` functions for managing continuation tokens.
- Ensured that pagination respects maximum page size limits defined in configuration.

src/handlers/setup.ts

@@ -1,7 +1,8 @@
 import { Env, DEFAULT_DEV_SECRET } from '../types';
 import { StorageService } from '../services/storage';
-import { jsonResponse, errorResponse } from '../utils/response';
-import { handleRegisterPage } from './setupPage';
+import { jsonResponse, errorResponse, htmlResponse } from '../utils/response';
+import { renderRegisterPageHTML } from '../setup/pageTemplate';
+import { LIMITS } from '../config/limits';
 
 type JwtSecretState = 'missing' | 'default' | 'too_short';
 
@@ -10,10 +11,19 @@ function getJwtSecretState(env: Env): JwtSecretState | null {
   if (!secret) return 'missing';
   // Block common "forgot to change" sample value (matches .dev.vars.example)
   if (secret === DEFAULT_DEV_SECRET) return 'default';
-  if (secret.length < 32) return 'too_short';
+  if (secret.length < LIMITS.auth.jwtSecretMinLength) return 'too_short';
   return null;
 }
 
+async function handleRegisterPage(request: Request, env: Env, jwtState: JwtSecretState | null): Promise<Response> {
+  const storage = new StorageService(env.DB);
+  const disabled = await storage.isSetupDisabled();
+  if (disabled) {
+    return new Response(null, { status: 404 });
+  }
+  return htmlResponse(renderRegisterPageHTML(jwtState));
+}
+
 // GET / - Setup page
 export async function handleSetupPage(request: Request, env: Env): Promise<Response> {
   const storage = new StorageService(env.DB);