feat: add config source prefix syntax for loading servers from IDE configs

[victoraraujo105]

Summary

Add support for running MCP servers directly from IDE/editor configs using a prefix syntax like claude-code:firecrawl or cursor:myserver.

This loads the full server config (command, args, env vars) from the specified config source and runs the server with proper environment.

Problem solved: Previously, mcp alias add only stored the command string, losing environment variables. This feature lets users leverage their existing IDE configs without re-registering servers.

Supported Prefixes

• claude-code (from ~/.claude.json)
• claude-desktop (from Claude Desktop config)
• cursor (from Cursor settings)
• vscode / vscode-insiders
• windsurf

Usage Examples

# Use firecrawl server from Claude Code config (with env vars!)
mcp tools claude-code:firecrawl

# Call a tool on a server from Cursor config
mcp call cursor:myserver tool_name --params '{"key": "value"}'

# Use playwright from Claude Desktop
mcp tools claude-desktop:playwright

# Mix with existing syntax
mcp tools claude-code:firecrawl   # From Claude config
mcp tools myalias                  # From aliases.json
mcp tools npx -y @mcp/server       # Direct command

Changes

• Add ParseConfigPrefix() to parse source:server format
• Add GetServerFromConfigSource() to load server config from IDE configs
• Update CreateClientFunc to handle prefix syntax before alias lookup
• Add comprehensive unit tests for prefix parsing (13 test cases)

Test Plan

• All existing tests pass (make test)
• Linter passes (make lint)
• Tested with real Claude Code config (~/.claude.json)
• Verified env vars are properly passed to spawned server

Notes

• Headers for SSE servers are not yet supported (noted in code)
• Uses existing scanMCPServersConfig and scanVSCodeConfig functions from configs.go