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/tests/test_structured_output.rs

@@ -1,7 +1,7 @@
 //cargo test --test test_structured_output --features "client server macros"
 use rmcp::{
     Json, ServerHandler,
-    handler::server::{router::tool::ToolRouter, tool::Parameters},
+    handler::server::{router::tool::ToolRouter, tool::IntoCallToolResult, wrapper::Parameters},
     model::{CallToolResult, Content, Tool},
     tool, tool_handler, tool_router,
 };
@@ -266,12 +266,12 @@ async fn test_output_schema_requires_structured_content() {
     assert!(calculate_tool.output_schema.is_some());
 
     // Directly call the tool and verify its result structure
-    let params = rmcp::handler::server::tool::Parameters(CalculationRequest { a: 5, b: 3 });
+    let params = Parameters(CalculationRequest { a: 5, b: 3 });
     let result = server.calculate(params).await.unwrap();
 
     // Convert the Json<CalculationResult> to CallToolResult
     let call_result: Result<CallToolResult, rmcp::ErrorData> =
-        rmcp::handler::server::tool::IntoCallToolResult::into_call_tool_result(result);
+        IntoCallToolResult::into_call_tool_result(result);
 
     assert!(call_result.is_ok());
     let call_result = call_result.unwrap();