chore: cleanup duplicate trade save, misleading cycle counters, and /api/summary inconsistencies

Bug #5: metrics.record_trade() only delegated to save_trade(), which
executor.execute() already calls — every trade was written twice (deduped
only by ON CONFLICT DO NOTHING). Remove the redundant call and the now-dead
method. RealExecutor.execute() raises NotImplementedError, so real mode is
unaffected.

Bug #6 (CYCLE SUMMARY): manifold accepted/rejected counters only increment
on the active-signal path, so with MANIFOLD_SIGNAL_ENABLED=false they always
printed 0/0 — print 'manifold_signal: disabled' instead.
family_conflicts_prevented duplicated blocked_by_family (same counter
printed twice); removed. gnews_cap was a dead variable with a misleading
comment; removed.

Bug #7 (/api/summary): total_trades was len() over a LIMIT-500 query —
capped once history grows; counts now come from COUNT(*) via
compute_metrics_from_db. cash_available was reimplemented in the API;
extract cash_available() in paper.py (same formula, unchanged) and feed it
from get_open_position_data() — the exact source/helper
PaperExecutor.initialize() uses. Test asserts API and executor report
identical cash for the same DB state.

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

bot/metrics/tracker.py

@@ -21,7 +21,6 @@ import logging
 from datetime import datetime, UTC
 
 from bot.data.db import Database
-from bot.executor.paper import Trade
 
 log = logging.getLogger(__name__)
 
@@ -30,11 +29,6 @@ class MetricsTracker:
     def __init__(self, db: Database) -> None:
         self._db = db
 
-    async def record_trade(self, trade: Trade) -> None:
-        """Persist a trade to the DB. No in-memory accumulation."""
-        await self._db.save_trade(trade)
-        log.info("Trade recorded: %s", trade)
-
     async def update_daily_summary(self) -> None:
         """Compute metrics from DB and write a metrics_daily snapshot.