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/README.md

@@ -83,6 +83,16 @@ A working MCP server demonstrating elicitation for user name collection.
 - JSON Schema validation with schemars
 - Tools: `greet_user` (collects name), `reset_name` (clears stored name)
 
+### Prompt Standard I/O Server (`prompt_stdio.rs`)
+
+A server demonstrating the prompt framework capabilities.
+
+- Shows how to implement prompts in MCP servers
+- Provides code review and debugging prompts
+- Demonstrates prompt argument handling with JSON schema
+- Uses standard I/O transport
+- Good example of prompt implementation patterns
+
 ## How to Run
 
 Each example can be run using Cargo:
@@ -111,6 +121,9 @@ cargo run --example servers_simple_auth_sse
 
 # Run the elicitation standard I/O server
 cargo run --example servers_elicitation_stdio
+
+# Run the prompt standard I/O server
+cargo run --example servers_prompt_stdio
 ```
 
 ## Testing with MCP Inspector