Gracefully skips figment tests when system Cairo library is unavailable
instead of crashing with opaque OSError during test collection.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Implements the core figment plugin: timer-driven SVG selection, REVEAL →
HOLD → DISSOLVE state machine, trigger API, and get_figment_state() for
overlay rendering. process() is a deliberate no-op; scroll.py will call
get_figment_state() instead.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>