Add MCP server for AI assistant integration

[vpetersson]

Implement a Model Context Protocol (MCP) server as a new subcommand (screenly mcp) that exposes the Screenly v4 API as tools for AI assistants like Claude, Cursor, and others.

Features:

• 31 MCP tools covering screens, assets, playlists, labels, and Edge Apps
• Stdio transport for seamless AI assistant integration
• Reuses existing CLI authentication (API_TOKEN env var or ~/.screenly)
• Comprehensive test coverage with 35 new unit tests

New files:

• src/mcp/mod.rs - Module structure
• src/mcp/server.rs - MCP server handler with tool definitions
• src/mcp/tests.rs - Unit tests for all tools
• src/mcp/tools/*.rs - Tool implementations for each API resource

Dependencies:

• Add rmcp 0.12 (MCP SDK) and schemars 0.8 (JSON Schema)
• Update sentry 0.42 -> 0.46, simple_logger 4 -> 5
• Update dev deps: httpmock 0.6 -> 0.8, swc_common 14 -> 18, swc_ecma_parser 24 -> 32

Other changes:

• Update httpmock API calls (body_contains -> body_includes, assert_hits -> assert_calls)
• Remove unused SettingValue struct in edge_app/setting.rs
• Comment out nightly-only rustfmt options to avoid warnings
• Update README with MCP documentation and configuration examples

[Copilot]

Pull request overview

This PR implements a Model Context Protocol (MCP) server as a new subcommand (screenly mcp) that exposes the Screenly v4 API as tools for AI assistants like Claude and Cursor.

Changes:

• Added 31 MCP tools across screens, assets, playlists, labels, and Edge Apps with stdio transport
• Integrated rmcp 0.12 and schemars 0.8 dependencies for MCP functionality
• Updated several dependencies (sentry 0.42→0.46, simple_logger 4→5, httpmock 0.6→0.8, swc packages)
• Added comprehensive test coverage with 35 unit tests
• Updated httpmock API usage and removed unused code

Reviewed changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/mcp/mod.rs	Module structure for MCP server
src/mcp/server.rs	Main MCP server handler with 31 tool definitions
src/mcp/tests.rs	Unit tests for all MCP tools
src/mcp/tools/*.rs	Tool implementations for each API resource (screens, assets, playlists, labels, edge apps)
src/main.rs	Added mcp module import
src/cli.rs	Added Mcp subcommand and handler function
Cargo.toml	Added MCP dependencies and updated versions
README.md	Added MCP documentation and configuration examples
rustfmt.toml	Commented out nightly-only options
src/commands/edge_app/setting.rs	Removed unused SettingValue struct
src/commands/edge_app/app.rs	Updated httpmock API calls
src/commands/playlist.rs	Updated httpmock API calls

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[renatgalimov]

Approved, but I'd like to get @sergey-borovkov's review too.