test: add pytest.importorskip for cairosvg-dependent tests

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>

tests/test_figment.py

@@ -3,6 +3,10 @@
 import os
 from enum import Enum
 
+import pytest
+
+pytest.importorskip("cairosvg", reason="cairosvg requires system Cairo library")
+
 from effects_plugins.figment import FigmentEffect, FigmentPhase, FigmentState
 from engine.effects.types import EffectConfig, EffectContext