feat: add Abathur persona mode

[octo-patch]

Fixes #9

Problem

Caveman is the only available persona. Issue #9 requested an Abathur mode (StarCraft II's master evolutionary biologist) as an alternative persona with the same efficiency goals but a biological/scientific flavor.

Solution

Add skills/abathur/SKILL.md implementing the Abathur persona:

Before:

"Sure! I'd be happy to help you with that. The issue you're experiencing is likely caused by your component creating a new object reference on each render cycle."

After (full mode):

"Specimen. New ref each render. Inline prop = new ref = re-render. Evolve: useMemo."

Vocabulary mapping:

• "Evolve:" → recommend/change to
• "Specimen" → component/function/module
• "Mutation" → code change/fix
• "Efficiency" → performance
• "Sequence" → process/steps

Supports same features as caveman:

• Three intensity levels: lite / full / ultra
• Auto-Clarity (drops persona for security warnings and destructive ops)
• "stop abathur" / "normal mode" to revert

Testing

The skill follows the same structure as skills/caveman/SKILL.md. Tested manually: loading the SKILL.md as a system prompt produces correct Abathur-style responses at all three intensity levels.