Add an LLM fact-check pass over the generated briefing

After summarisation the report is verified against the collected
payload (numbers, directions, unsupported claims) by a second LLM call
with a Verification JSON schema. Major issues trigger one revision and
a re-check; minor-only verdicts are normalized to ok. Failures never
block delivery. The verdict is stored in the result JSON and shown on
the dashboard (badge + 검증 메모). Disable with US2KR_VERIFY_ENABLED.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

us2kr/pipeline.py

@@ -23,10 +23,10 @@ from us2kr.config import KST, Settings
 from us2kr.deliver import build_deliverers
 from us2kr.llm.base import LLMError
 from us2kr.market_time import MarketClock
-from us2kr.models import BriefingResult, MarketPayload, Report
+from us2kr.models import BriefingResult, MarketPayload, Report, Verification
 from us2kr.render import render_markdown
 from us2kr.store import Store
-from us2kr.summarize import build_provider, summarize_payload
+from us2kr.summarize import build_provider, summarize_payload, verify_and_revise
 from us2kr.symbols import SYMBOL_GROUPS
 
 log = logging.getLogger(__name__)
@@ -162,6 +162,18 @@ def _summarize(payload: MarketPayload, settings: Settings) -> tuple[Report | Non
         return None, None, f"{type(exc).__name__}: {exc}"
 
 
+def _verify(
+    payload: MarketPayload, report: Report, settings: Settings
+) -> tuple[Report, Verification | None]:
+    """Fact-check (and possibly revise) the report. Any failure keeps the report and returns None."""
+    try:
+        provider = build_provider(settings)
+        return verify_and_revise(payload, report, provider)
+    except Exception as exc:  # noqa: BLE001 - verification must never block the briefing
+        log.warning("verification failed, delivering unverified report: %s: %s", type(exc).__name__, exc)
+        return report, None
+
+
 def _superseded_before_krx_open(session: date, krx_date: date, clock: MarketClock) -> bool:
     """True when another US session closes before KRX next trades, so this briefing would be stale.
 
@@ -271,6 +283,7 @@ def run_briefing(
         report: Report | None = None
         model_used: str | None = None
         error: str | None = None
+        verification: Verification | None = None
         degraded = False
         if no_llm:
             degraded = True
@@ -278,6 +291,8 @@ def run_briefing(
         else:
             report, model_used, error = _summarize(payload, settings)
             degraded = report is None
+            if report is not None and settings.verify_enabled:
+                report, verification = _verify(payload, report, settings)
 
         markdown = render_markdown(payload, report, model_used)
         result = BriefingResult(
@@ -287,6 +302,7 @@ def run_briefing(
             model_used=model_used,
             degraded=degraded,
             error=error,
+            verification=verification,
         )
         if dry_run:
             print(markdown)