Add Master Archive specialist agent

[angnuoli]

Summary

• document the five MicroClaw hero scenarios
• add Master Archive as the first specialist Agent template with an independent OpenClaw persona workspace
• make OpenClaw agents.list the runtime source of truth for the sidebar while using one shared catalog only for New Agent templates and UI metadata
• keep new installations main-only; add a Popular Agent to OpenClaw and the sidebar only after transactional config, workspace, and Gateway activation succeeds
• preserve existing custom OpenClaw Agents and harden roster migration, path resolution, process ownership, and refresh failures

Validation

• desktop: npx vitest run src/agent-personas.test.ts src/path-resolver.test.ts src/gateway-lifecycle.test.ts
• desktop/renderer: npx vitest run src/stores/agents.test.ts
• desktop: npm run build