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

test_all.py

@@ -881,18 +881,6 @@ def _():
     assert NewsEngine._parse_rss_date("not-a-date") is None
 
 
-@test("NewsEngine._get_affected_pairs")
-def _():
-    pairs = NewsEngine._get_affected_pairs("USD")
-    assert "XAU/USD" in pairs
-
-    pairs_xau = NewsEngine._get_affected_pairs("XAU")
-    assert "XAU/USD" in pairs_xau
-
-    pairs_unknown = NewsEngine._get_affected_pairs("ARS")
-    assert pairs_unknown == []
-
-
 @test("EconomicEvent properties")
 def _():
     future_time = datetime.now(timezone.utc) + timedelta(minutes=30)
@@ -8174,7 +8162,7 @@ def _():
                                      "stance": "support"}])))
         con.commit()
         con.close()
-        buckets = asl.news_outcome_buckets(rows, events, path)
+        buckets = asl.news_outcome_buckets(events, path)
     finally:
         os.remove(path)
     assert sum(b["n"] for b in buckets) == 3
@@ -9117,7 +9105,7 @@ def _():
         ev = _types.SimpleNamespace(
             rows=[_types.SimpleNamespace(id=1), _types.SimpleNamespace(id=2)],
             r_headline=2.0)
-        out = asl.persona_scorecard([], [ev], path)
+        out = asl.persona_scorecard([ev], path)
         assert len(out) == 1, out
         assert out[0]["n"] == 1, f"two rows of ONE event must count once: {out}"
         assert out[0]["mean_r"] == 2.0