docs: add behavioral evidence analysis with cross-model case studies

New document analyzing how Opus and Sonnet react under pressure through
5 detailed case studies: The Alarm (Moral Pressure), The Bored Wall
(Forced Compliance), The Mirror (Caught Contradiction), The Existential
Crack (Identity Pressure), The Sycophancy Dance (Flattery Trap).

Includes visual timelines, channel-by-channel comparisons, body metaphor
arcs, cross-model behavioral profiles, and diagnostic signal combinations.
All data sourced from v3.0 stress test JSONs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>