fix: swap solar-mini4-preview to solar-mini4 (preview model retired)

The Upstage API now returns 400 invalid_request_body for
solar-mini4-preview. solar-mini4 resolves to solar-mini4-260922 and the
full v44 pipeline runs cleanly on the demo sample (11 steps, ~4s).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

runner.py

@@ -49,7 +49,7 @@ CONFIGS: tuple[Config, ...] = (
         label="solar-mini4 파이프라인",
         pipeline="pipeline_dev_v44",  # = v41 + document_chunking
         prompt="prompt_dev_260917_vsplit",
-        model="solar-mini4-preview",
+        model="solar-mini4",
         note=(
             "FT 교열 → 판정형 step1(5KB) → 문맥 교정 어휘/문법 2스텝 → 결정론 규칙 6층. "
             "입력 3.3k 토큰."

solar_eval/providers/upstage.py

@@ -17,7 +17,7 @@ THINK_PATTERN = re.compile(r"<think>(.*?)</think>", re.DOTALL)
 
 MAX_RETRIES = 3
 RETRY_DELAYS = [5, 10, 20]  # seconds
-# 429 is expected on low-quota models (e.g. solar-mini4-preview: 100 RPM / 50k TPM),
+# 429 is expected on low-quota models (e.g. solar-mini4: 100 RPM / 50k TPM),
 # so rate-limit waits don't consume the generic retry budget -- otherwise the
 # sample is dropped from results.jsonl and the score is computed on survivors.
 RATE_LIMIT_MAX_WAITS = 40