feat(parser): add comprehensive Cognito trigger schemas

- Implemented 12 new Zod schemas for Cognito Lambda triggers:
  - Pre-Signup, Post-Confirmation, Pre-Authentication, Post-Authentication
  - Pre-Token Generation (V1 & V2), Migrate User
  - Custom Message, Custom Email Sender, Custom SMS Sender
  - Define Auth Challenge, Create Auth Challenge, Verify Auth Challenge
- Updated schemas/index.ts for dedicated exports
- Added unit tests in cognito.test.ts following Prepare/Act/Assess format

Author: VatsalGoel3

packages/parser/package.json

@@ -72,6 +72,10 @@
       "require": "./lib/cjs/schemas/cloudwatch.js",
       "import": "./lib/esm/schemas/cloudwatch.js"
     },
+    "./schemas/cognito": {
+      "require": "./lib/cjs/schemas/cognito.js",
+      "import": "./lib/esm/schemas/cognito.js"
+    },
     "./schemas/dynamodb": {
       "require": "./lib/cjs/schemas/dynamodb.js",
       "import": "./lib/esm/schemas/dynamodb.js"
@@ -183,6 +187,10 @@
         "./lib/cjs/schemas/cloudwatch.d.ts",
         "./lib/esm/schemas/cloudwatch.d.ts"
       ],
+      "schemas/cognito":[
+        "./lib/cjs/schemas/cognito.d.ts",
+        "./lib/esm/schemas/cognito.d.ts"
+      ],
       "schemas/dynamodb": [
         "./lib/cjs/schemas/dynamodb.d.ts",
         "./lib/esm/schemas/dynamodb.d.ts"