Fix sidebar username, Signals filter clarity and layout

- JWT now carries a username claim; sidebar shows "Signed in as <name>"
  instead of the bare user id (sub). Re-login required for the new claim.
- Signals: Min R:R / Min Confidence inputs reflect the effective filter —
  auto-filled from the activation gate when "Qualified only" is on, reset
  to 0 when off (no more misleading 0 while the gate is active).
- Signals layout: Run Scanner moved to its own action row (it's a job
  trigger, not a filter); qualified toggle grouped with the refinement
  filters under one Filters panel.

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

tests/unit/test_rr_scanner_integration.py

@@ -19,7 +19,7 @@ from app.models.score import CompositeScore
 from app.models.sr_level import SRLevel
 from app.models.ticker import Ticker
 from app.models.trade_setup import TradeSetup
-from app.services.rr_scanner_service import scan_ticker, _compute_quality_score
+from app.services.rr_scanner_service import scan_ticker
 
 
 # ---------------------------------------------------------------------------
@@ -183,8 +183,6 @@ async def test_scan_ticker_full_flow_quality_selection_and_persistence(
     assert long_setup.entry_price == pytest.approx(expected_entry, abs=0.5)
     assert short_setup.entry_price == pytest.approx(expected_entry, abs=0.5)
 
-    entry = long_setup.entry_price  # actual entry for R:R calculations
-
     # -- Assert: stop_loss values --
     # ATR ≈ 2.0, risk = ATR × 1.5 = 3.0
     # Long stop = entry - risk, Short stop = entry + risk