feat: add discover-skill command (clean-room skill importer)

[neural-claw]

Adds /meta:discover-skill — a command that searches skills.sh for existing community skills, audits them for security threats, extracts useful patterns, and generates a clean-room skill in our plugin structure.

Flow

1. Search skills.sh + GitHub for matching skills
2. Audit each for 6 threat categories (shell exec, exfil, prompt injection, fs escape, untrusted network, obfuscation) → SAFE / CAUTION / UNSAFE
3. Generate a new skill written from scratch, inspired by safe patterns
4. Report findings with security ratings and attribution

Key principle

We use the ecosystem as an intelligence feed, not a dependency. Never copy verbatim, never include UNSAFE patterns, always attribute inspiration.

Placed in plugins/meta/commands/ alongside other primitive generators.

[NeuralEmpowerment]

Closing — the discover-skill concept is interesting but skills.sh is a fragile external dependency for a baked-in primitive. Worth revisiting if there's a more self-contained approach.