feat: add 7 built-in middleware components inspired by Hono.js

New Middleware:
- CORS: Cross-Origin Resource Sharing with full configuration support
- Cookie Helper: Cookie management with signed cookie support (HMAC-SHA256)
- JWT: JSON Web Token authentication (HS256/384/512)
- Bearer Auth: Simple Bearer token authentication
- Compression: Gzip and deflate response compression
- Rate Limiting: Request rate limiting with customizable stores
- Validator: Schema-based request validation

Features:
- Context store for middleware data sharing (get/set/get_client_ip)
- Middleware export module with utility functions
- Comprehensive property-based tests for all middleware
- Example file demonstrating all middleware usage

Files Added:
- cors.v, cookie.v, jwt.v, bearer_auth.v, compress.v, rate_limit.v, validator.v
- middleware.v (unified exports)
- examples/middleware_demo.v
- tests/test_*.v (9 new test files)

Documentation:
- Updated README.md with detailed middleware usage guide
- Added Schema Builder API documentation

.gitignore

@@ -45,3 +45,5 @@ temp/
 
 # Chunk upload temp files
 chunks/
+
+.kiro