feat(model): add json schema generation support for all model types

This commit adds JSON Schema support for all model types by implementing `schemars::JsonSchema` trait. The feature is gated behind the new `schemars` feature flag. This enables automatic schema generation for API documentation and validation purposes. Added tests to verify schema generation for client and server JSON-RPC messages.

Author: shorwood

README.md

@@ -192,6 +192,7 @@ See [examples](examples/README.md)
 - `client`: use client side sdk
 - `server`: use server side sdk
 - `macros`: macros default
+- `schemars`: implement `JsonSchema` for all model structs
 
 ### Transports
 

crates/rmcp/Cargo.toml

@@ -28,7 +28,7 @@ paste = { version = "1", optional = true }
 oauth2 = { version = "5.0", optional = true }
 
 # for auto generate schema
-schemars = { version = "0.8", optional = true }
+schemars = { version = "0.8", optional = true, features = ["chrono"] }
 
 # for image encoding
 base64 = { version = "0.21", optional = true }
@@ -89,6 +89,7 @@ tower = ["dep:tower-service"]
 __auth = ["dep:oauth2", "dep:reqwest", "dep:url"]
 auth = ["__auth", "reqwest?/rustls-tls"]
 auth-tls-no-provider = ["auth", "reqwest?/rustls-tls-no-provider"]
+schemars = ["dep:schemars"]
 
 [dev-dependencies]
 tokio = { version = "1", features = ["full"] }