docs: Add guide for organizing larger FastMCP servers with versioned tools

[dgenio]

Summary

Adds documentation and examples for organizing larger FastMCP servers and managing tool versions.

Closes #1681

Changes

Documentation

• New: docs/server_organization.md - Comprehensive guide on:
  • Recommended project layout (server.py + tools/ structure)
  • Name-based tool versioning pattern (tool_v1, tool_v2)
  • When to create new versions vs. maintaining backward compatibility
  • Client consumption strategies (whitelists, version selection)
  • Advanced patterns (shared logic, deprecation)

Examples

• New: examples/snippets/servers/server_layout/ - Runnable example showing:
  • Organized tool structure with separate modules
  • Two versions of a tool (get_info_v1, get_info_v2) demonstrating breaking changes
  • Clean separation between server wiring and tool implementation

Other Changes

• Updated mkdocs.yml to include new docs page in navigation
• Updated examples/snippets/servers/__init__.py to include new example

Design Decisions

• Name-based versioning: Uses tool names like get_info_v1, get_info_v2 - compatible with current main branch, no protocol changes needed
• No dependency on unmerged PRs: This pattern works with the SDK as-is today
• Docs-only scope: No modifications to core library behavior under src/mcp/
• Follows existing patterns: Consistent with other snippet examples and documentation style

Testing

Run the example: uv run examples/snippets/servers/server_layout/server.py## Checklist

• [x] Documentation follows existing style and conventions
• [x] Example code uses proper type hints
• [x] Example follows existing snippet patterns
• [x] No changes to core library behavior
• [x] mkdocs.yml navigation updated
• [x] Code passes ruff formatting/linting
• [x] Example is runnable and self-contained