Extends the attention anchor system with three representative blocks from
the concept-formation/identity zone (20-35) which handles character
appearance, body proportions, and distinguishing visual traits.
- IDENTITY_BLOCKS = [21, 26, 31]: evenly spaced across the identity zone
- sigma gate (0.2, 0.55): mid-sigma window where identity is being formed,
slightly later than semantic anchors (0.2, 0.5)
- max inject strength 12% (vs 28% for semantic anchors): lighter touch to
preserve appearance without overriding scene-specific action/composition
- Same blessed map file, same capture/bless/inject infrastructure
- _sigma_gated_strength now takes configurable sigma_high/sigma_low params
- _build_block_replacement takes sigma_gate tuple per block
Fix pre-existing test failures from single-word transition removal:
"suddenly" replaced with "cut to" in transition-related test prompts.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
