feat: enrich native harness orchestrator guidance

[mlaccetti]

Summary

• Add shared guidance for when orchestrators should use native goals, plans, TODO lists, and question tools, with evidence-based continuation and event-driven waits.
• Add concrete Codex, Claude Code, Antigravity, and Cursor guidance. Claude's default agent now exposes native Agent, planning, TODO, and question tools.
• Replace Cursor's manual User Rules setup with a managed user-scoped local plugin generated from the installed kit; add stale-link verification and safe unlink ownership checks.

Validation

• go test ./...
• golangci-lint run ./...
• just check-no-sleep
• git diff --check
• Case-insensitive Kimi scan: no matches.

Cursor must be reloaded after linking for its local plugin discovery. Enterprise administrators can disable local plugin imports.