feat: Add prompt support (#351)

* feat: add prompt support with typed argument handling

- Implement #[prompt], #[prompt_router], and #[prompt_handler] macros
- Add automatic JSON schema generation from Rust types for arguments
- Support flexible async handler signatures with automatic adaptation
- Create PromptRouter for efficient prompt dispatch
- Include comprehensive tests and example implementation

This enables MCP servers to provide reusable prompt templates that
LLMs can discover and invoke with strongly-typed parameters, similar
to the existing tool system but optimized for prompt use cases.

🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>

* refactor: unify parameter handling between tools and prompts

- Replace Arguments<T> with Parameters<T> for consistent API
- Create shared common module for tool/prompt utilities
- Modernize async handling with futures::future::BoxFuture
- Move cached_schema_for_type to common module for reuse
- Update error types from rmcp::Error to rmcp::ErrorData
- Add comprehensive trait implementations for parameter extraction

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor: extract Parameters wrapper to shared module and unify trait usage

- Move Parameters type from common.rs to dedicated wrapper/parameters.rs module
- Unify extractor traits by using FromContextPart for both tools and prompts
- Remove duplicate FromToolCallContextPart and FromPromptContextPart traits
- Add structured output support to Json wrapper with IntoCallToolResult impl
- Improve error messages with more descriptive panic for schema serialization
- Update all imports across codebase to use new module path
- Clean up trailing whitespace and formatting inconsistencies

This consolidates parameter extraction logic and reduces code duplication
between tool and prompt handlers while maintaining backward compatibility.

* chore: remove committed .egg-info directory and update gitignore

* docs: fix documentation formatting

crates/rmcp/src/service.rs

@@ -162,12 +162,12 @@ pub trait DynService<R: ServiceRole>: Send + Sync {
         &self,
         request: R::PeerReq,
         context: RequestContext<R>,
-    ) -> BoxFuture<Result<R::Resp, McpError>>;
+    ) -> BoxFuture<'_, Result<R::Resp, McpError>>;
     fn handle_notification(
         &self,
         notification: R::PeerNot,
         context: NotificationContext<R>,
-    ) -> BoxFuture<Result<(), McpError>>;
+    ) -> BoxFuture<'_, Result<(), McpError>>;
     fn get_info(&self) -> R::Info;
 }
 
@@ -176,14 +176,14 @@ impl<R: ServiceRole, S: Service<R>> DynService<R> for S {
         &self,
         request: R::PeerReq,
         context: RequestContext<R>,
-    ) -> BoxFuture<Result<R::Resp, McpError>> {
+    ) -> BoxFuture<'_, Result<R::Resp, McpError>> {
         Box::pin(self.handle_request(request, context))
     }
     fn handle_notification(
         &self,
         notification: R::PeerNot,
         context: NotificationContext<R>,
-    ) -> BoxFuture<Result<(), McpError>> {
+    ) -> BoxFuture<'_, Result<(), McpError>> {
         Box::pin(self.handle_notification(notification, context))
     }
     fn get_info(&self) -> R::Info {