feat(wave2-3): Amygdala/Brain + Formula generation complete (#477)

Wave 2: brain_amygdala, brain_basal_ganglia, brain_hippocampus
Wave 3: math_formula, formula_discovery, formula_discovery_engine

Generated via vibee (AGENT MU verifications PASSED).
.t27 files excluded pending tri27 CLI signature support.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Antigravity Agent