feat(svrnty-vision): Phase 4b complete — full impl + e2e test suite

- palette.py + rembg.py: implement from stubs (Pillow median-cut + rembg u2net)
- vlm.py: rename Spark2→steev (Strix Halo / Ollama); bump max_tokens 1024→4096
  (qwen3-vl:32b thinking mode consumes budget tokens — 4096 min for valid output)
- settings.py: rename spark2_vlm_*/spark1_flux_* → vlm_*/flux_*; real defaults
  (steev 100.88.167.87:11434 Ollama, gx10 100.90.100.10:8188 ComfyUI)
- tests/: conftest.py + test_palette.py + test_rembg.py + test_integration_e2e.py
  (28 unit + 10 integration; 38/38 passing — VLM raw/polished/ugc + FLUX render)
- CLAUDE.md: rewrite to accurate phase status + infra + layout
- requirements.txt + pyproject.toml: add Pillow, rembg, pytest-asyncio deps

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_flux_workflow.py

@@ -43,7 +43,7 @@ def test_render_requires_workflow_or_prompt() -> None:
     assert response.status_code == 400
 
 
-def test_render_returns_502_when_spark1_unreachable() -> None:
+def test_render_returns_502_when_gx10_unreachable() -> None:
     class _StubClient:
         def __init__(self, *a, **kw):
             pass