replay 2.0

• added 'gate' - cached task execution tool, gating child execution based on declared inputs and outputs
• added optional sandbox to 'replay' (and 'gate') - with auto-sandboxing based on inputs and outputs declared in a playlist
• added optional stdio MCP server capability to 'replay' (for AI agents)
• added support for glob patterns in 'replay' playlists - with automatic dependency detection for glob inputs/outputs
• new actions added to 'replay'
• enhancements to 'fingerprint': snapshots, snapshot comparison, glob pattern exclusion
• internal major re-write of majority of code to remove Obj-C and use cpp