Help users choose and reuse project guidance, skills, commands, and named agents #2392

Reader need

"I keep asking for the same review or workflow. Should I make it a project instruction, skill, slash command, or named agent?"

Current gap

user-docs/features/agent-behavior/project-instructions-and-rules.md, skills-commands-and-soul.md, and named-agents.md cover individual mechanisms. Readers need a decision guide and one complete reusable workflow that connects setup to actual use.

Proposed work

Add a task-oriented entry point under Use Mecatl that helps readers choose among persistent repository guidance, on-demand procedures, prompt templates, and reusable specialist agents. Work through one concrete example, such as a reusable reviewer, and link to the existing owners for exact discovery, trust, tools, and configuration behavior.

Acceptance criteria

• Readers can choose a mechanism based on whether they need general project guidance, a reusable procedure, a prompt template, or a specialist with scoped tools/instructions.
• The worked example includes the minimal artifact/configuration, a prompt or command to use it, and a way to verify that it was discovered and used.
• Explain relevant trust, restart/reload, configuration ownership, and remote-server limits without duplicating the capability pages.
• Clearly distinguish named-definition inventory from running agents, linking to the delegation workflow in Document common mecatui delegation workflows #1718.
• Check the available session-agent selection surface, including mecatui: finish /agent integration for session-scoped agent definitions #2384, before promising client /agent behavior; the guide must describe shipped usage.
• Reuse and cross-link existing pages wherever that serves the task; avoid a parallel reference inventory.

Tracking

Part of #2386. Follow the parent issue's shared ownership and validation criteria.