feat: add MCP server profile scope isolation

Implements scope: profile for MCP servers, enabling true isolation where servers are visible only when using a specific profile command.

Profile-scoped servers are stored in {command}-mcp.json and loaded via --strict-mcp-config --mcp-config flags, preventing cross-contamination between different environment profiles.

Key changes:
- Add create_mcp_config_file() to generate profile MCP config JSON
- Modify configure_all_mcp_servers() to separate profile from regular servers
- Update launcher scripts to detect and use --strict-mcp-config when profile servers exist
- Add 15+ tests covering all profile scope scenarios

Author: alex-feel