Add multi-factor conviction gate to activation

Make "qualified" mean an edge candidate, not just R:R + confidence.
The gate now also requires (all admin-configurable, defaults on):
- high conviction: recommended_action LONG_HIGH / SHORT_HIGH only
- clean read: risk_level Low (no contradicting signals)
- probable primary target: best target probability >= min (default 60)

- Shared predicate: app/services/qualification.py +
  frontend/src/lib/qualification.ts (mirrored)
- Activation config extended (min_target_probability,
  require_high_conviction, exclude_conflicts) with bool-aware
  get/update + validation
- /trades/performance switched to ?qualified_only=true, applying
  the full gate server-side; confidence breakdown stays unfiltered
- Dashboard "Qualified", Signals "Qualified only" toggle, and
  Track Record all use the one gate; Admin gains the new controls

Sentiment provider runtime config (prior change) included.

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

tests/unit/test_outcome_service.py

@@ -289,7 +289,15 @@ class TestGetPerformanceStats:
         ))
         await db_session.flush()
 
-        stats = await get_performance_stats(db_session, min_rr=2.0, min_confidence=70.0)
+        # Gate on R:R + confidence only (conviction filters off for this test)
+        config = {
+            "min_rr": 2.0,
+            "min_confidence": 70.0,
+            "min_target_probability": 0.0,
+            "require_high_conviction": False,
+            "exclude_conflicts": False,
+        }
+        stats = await get_performance_stats(db_session, config=config)
 
         # Overall covers only the qualified setup
         assert stats["overall"]["total"] == 1