Add modular primitive libraries and fix Symbol class compatibility

- Add primitive_libs/ with modular primitive loading (core, math, image,
  color, color_ops, filters, geometry, drawing, blending, arrays, ascii)
- Effects now explicitly declare dependencies via (require-primitives "...")
- Convert ascii-fx-zone from hardcoded special form to loadable primitive
- Add _is_symbol/_is_keyword helpers for duck typing to support both
  sexp_effects.parser.Symbol and artdag.sexp.parser.Symbol classes
- Auto-inject _interp and _env for primitives that need them
- Remove silent error swallowing in cell_effect evaluation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

run_staged.py

@@ -118,6 +118,7 @@ def run_staged_recipe(
         "output_step_id": plan.output_step_id,
         "analysis": analysis_data,
         "effects_registry": plan.effects_registry,
+        "minimal_primitives": plan.minimal_primitives,
         "steps": [],
     }