[FEATURE] [RPC] Implement Router and Handler Trait

[hulxv]

Description

Create the routing system and handler trait that forms the core of the RPC framework.

Motivation

Allow users to register handlers for different RPC methods with type safety.

Proposed Solution

pub trait Handler: Send + Sync {
    fn call(&self, req: Request) -> BoxFuture<'static, Result<Response>>;
}

pub struct Router {
    routes: Map<String, Box<dyn Handler>>,
}

Tasks

• Design Handler trait
• Implement Router
• Add route registration
• Support wildcard routes
• Add route conflict detection
• Write tests for routing logic
• Document routing behavior

Expected

• Type-safe handler registration
• Efficient route lookup
• Conflict detection
• Wildcard support

Dependencies:

• Depends on [FEATURE] [RPC] Implement RPC Request/Response Types #39