feat(spec): ✍️ add mcp task job paradigm spec

[binggg]

Summary

• add initial spec for the MCP + skill + task/job-first paradigm
• define requirements, design, and implementation tasks under specs/mcp-task-job-paradigm/
• frame the evolution around converged domain tools, workflow-oriented skills, and first-class task control plane

Scope

• spec only, no runtime implementation yet
• intended as a WIP discussion draft for architecture alignment

Notes

• this PR focuses on how current queryXxx / manageXxx entrypoints can evolve toward task/job-first workflows
• it also proposes queryTasks / manageTasks as the cross-domain task control surface