docs: replace deprecated v1 createRouter/router.use with v2 app patterns

- security.md: createRouter() + router.use() → app.all()
- validate-data.md: router.use() → app.all() (3 occurrences)
- cors.ts JSDoc: createRouter() + router.use() → app.all()

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: productdevbook

docs/2.utils/4.security.md

@@ -103,8 +103,7 @@ If return value is not `false`, the request is handled and no further action is
 
 ```ts
 const app = new H3();
-const router = createRouter();
-router.use("/", async (event) => {
+app.all("/", async (event) => {
   const corsRes = handleCors(event, {
     origin: "*",
     preflight: {

docs/4.examples/validate-data.md

@@ -46,7 +46,7 @@ const contentSchema = v.object({
   uuid: v.pipe(v.string(), v.uuid()),
 });
 
-router.use(
+app.all(
   // You must use a router to use params
   "/content/:topic/:uuid",
   async (event) => {
@@ -166,7 +166,7 @@ const contentSchema = z.object({
   uuid: z.string().uuid(),
 });
 
-router.use("/content/:topic/:uuid", async (event) => {
+app.all("/content/:topic/:uuid", async (event) => {
   const params = await getValidatedRouterParams(event, contentSchema.safeParse);
   if (!params.success) {
     // Handle validation errors
@@ -187,7 +187,7 @@ const contentSchema = v.object({
   uuid: v.pipe(v.string(), v.uuid()),
 });
 
-router.use("/content/:topic/:uuid", async (event) => {
+app.all("/content/:topic/:uuid", async (event) => {
   const params = await getValidatedRouterParams(event, v.safeParser(contentSchema));
   if (!params.success) {
     // Handle validation errors

src/utils/cors.ts

@@ -126,8 +126,7 @@ export function appendCorsHeaders(event: H3Event, options: CorsOptions): void {
  *
  * @example
  * const app = new H3();
- * const router = createRouter();
- * router.use("/", async (event) => {
+ * app.all("/", async (event) => {
  *   const corsRes = handleCors(event, {
  *     origin: "*",
  *     preflight: {