chore: remove dead functions and write-only state (no behaviour change)

Zero callers anywhere (tests included), verified by grep/AST:
- dashboard_publisher.DashboardPublisher.publish_all (run_cycle inlines both publishes)
- signal_log.SignalLogger.advance_with_bars (the backfill script uses
  backfill_seeds / resolve_from_store / reseed_unresolvable) and the never-read
  SignalLogger.path property plus its write-only self._path
- llm_client.reset_llm_client (tests reset the singleton by assignment)
- market_outlook._last_run_ts, residue of the old "now - last < 3600" dedup;
  _last_run_hour (the UTC hour bucket) is the live key
- news_engine FundamentalContext.event_impact_on_pairs: written once, read by
  nothing; its only feeder NewsEngine._get_affected_pairs and that helper's
  unit test go with it
- position_sizing.LIVE_DEPTH_BARS (referenced only by its own docstring, which
  now states the depths inline), the unused Iterable import and the unused
  atr_ok parameter of _fill_geometry
- analyze_signal_log: unused `field` import and the unused `rows` parameter of
  persona_scorecard / news_outcome_buckets (both read the DB directly)

The two backfill/label scripts' --db help text now names the config.json
setting it actually falls back to.

Suite: 463 passed, 0 failed (one test removed with its subject).

Claude-Session: https://claude.ai/code/session_0156YhogLytzj9P2iH1skGbL

news_engine.py

@@ -223,7 +223,6 @@ class FundamentalContext:
     warning_message: str = ""
     news_sentiment: Dict[str, float] = field(default_factory=dict)  # currency -> sentiment
     news_headlines: List[NewsSentiment] = field(default_factory=list)
-    event_impact_on_pairs: Dict[str, str] = field(default_factory=dict)
     calendar_available: bool = False  # True if live calendar data was fetched
     llm_summary: str = ""  # DeepSeek market-context blurb (display-only)
 
@@ -415,15 +414,6 @@ class NewsEngine:
                     )
                     break
 
-            # Map upcoming high-impact events to affected pairs
-            for event in context.events_upcoming_1h:
-                if event.is_high_impact:
-                    affected = self._get_affected_pairs(event.currency)
-                    for pair in affected:
-                        context.event_impact_on_pairs[pair] = (
-                            f"{event.currency} {event.event} in {event.minutes_until:.0f}min"
-                        )
-
         except Exception as e:
             logger.warning(f"Economic calendar fetch failed: {e}")
 
@@ -1149,11 +1139,3 @@ class NewsEngine:
             except ValueError:
                 continue
         return None
-
-    @staticmethod
-    def _get_affected_pairs(currency: str) -> List[str]:
-        _MAP = {
-            "USD": ["XAU/USD"],
-            "XAU": ["XAU/USD"],
-        }
-        return _MAP.get(currency, [])