Add SwiftDoc MCP to Apple app plugins

[dimillian-oai]

Summary

• Add the SwiftDoc HTTP MCP server to the Build iOS Apps plugin alongside XcodeBuildMCP
• Add a plugin-local MCP config to Build macOS Apps and wire it from the plugin manifest
• Update the iOS and macOS plugin READMEs to mention SwiftDoc documentation lookup

Validation

• jq empty plugins/build-ios-apps/.codex-plugin/plugin.json plugins/build-ios-apps/.mcp.json plugins/build-macos-apps/.codex-plugin/plugin.json plugins/build-macos-apps/.mcp.json
• targeted Python manifest/MCP contract check
• git diff --check

Note: this public checkout does not include the internal scripts/validate_plugin.py; validation covered JSON syntax and the manifest-to-MCP wiring for both touched plugins.