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

examples/servers/src/elicitation_stdio.rs

@@ -7,7 +7,7 @@ use std::sync::Arc;
 use anyhow::Result;
 use rmcp::{
     ErrorData as McpError, ServerHandler, ServiceExt, elicit_safe,
-    handler::server::{router::tool::ToolRouter, tool::Parameters},
+    handler::server::{router::tool::ToolRouter, wrapper::Parameters},
     model::*,
     schemars::JsonSchema,
     service::{RequestContext, RoleServer},
@@ -42,6 +42,15 @@ pub struct ElicitationServer {
     tool_router: ToolRouter<ElicitationServer>,
 }
 
+impl ElicitationServer {
+    pub fn new() -> Self {
+        Self {
+            user_name: Arc::new(Mutex::new(None)),
+            tool_router: Self::tool_router(),
+        }
+    }
+}
+
 impl Default for ElicitationServer {
     fn default() -> Self {
         Self::new()
@@ -50,13 +59,6 @@ impl Default for ElicitationServer {
 
 #[tool_router]
 impl ElicitationServer {
-    pub fn new() -> Self {
-        Self {
-            user_name: Arc::new(Mutex::new(None)),
-            tool_router: Self::tool_router(),
-        }
-    }
-
     #[tool(description = "Greet user with name collection")]
     async fn greet_user(
         &self,