fix: weekend-aware cycle — IVGate, pandas MultiIndex, ticker aliases, day/session in AI prompt

- auto_cycle.py: detect weekend/market session, build cycle_meta with day_of_week/is_weekend/market_note;
  IVGate skips iv_rank>=99 on weekends to avoid artificial weekend option premium cascade;
  inject portfolio context (open trades + price moves + concentration) before AI scoring;
  pass portfolio_context_block + run_id to both AI scorer and suggester
- ai_analyzer.py: _build_temporal_news_block injects market session banner (WEEKEND warning,
  pre/after-market note, or open session label) so AI knows markets are closed and defers execution to Monday
- iv_engine.py: add WHEAT/EUR/USD ticker aliases; skip saving IV snapshots on weekends to protect history;
  resolve aliases before slash-format conversion in _resolve_ticker
- technical_indicators.py: fix pandas MultiIndex from yfinance>=0.2 (droplevel+squeeze);
  use period proportional to lookback instead of fixed period=1d
- database.py: asset_class ticker-based fallback (_asset_class_from_ticker); one-time backfill migration
  for all NULL asset_class rows; ai_call_logs table + save/get helpers; normalize_ticker public function

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/services/database.py

@@ -1069,6 +1069,45 @@ def _normalize_yf_ticker(ticker: str) -> str:
     return t
 
 
+# Common AI hallucinations / wrong ticker formats → canonical Yahoo Finance symbols
+TICKER_ALIASES: dict = {
+    # Commodities
+    "WHEAT": "ZW=F", "CORN_FUTURES": "ZC=F", "SOYBEANS": "ZS=F", "SOYBEAN": "ZS=F",
+    "CRUDE": "CL=F", "OIL": "CL=F", "WTI": "CL=F", "BRENT": "BZ=F",
+    "CRUDE OIL": "CL=F", "NATURAL GAS": "NG=F",
+    "GOLD": "GC=F", "SILVER": "SI=F", "COPPER": "HG=F", "PLATINUM": "PL=F",
+    "SUGAR": "SB=F", "COFFEE": "KC=F", "COCOA": "CC=F", "COTTON": "CT=F",
+    # Forex — "/" format → yfinance format
+    "EUR/USD": "EURUSD=X", "USD/EUR": "EURUSD=X",
+    "USD/JPY": "USDJPY=X", "JPY/USD": "USDJPY=X",
+    "GBP/USD": "GBPUSD=X", "USD/GBP": "GBPUSD=X",
+    "USD/CHF": "USDCHF=X", "CHF/USD": "USDCHF=X",
+    "AUD/USD": "AUDUSD=X", "USD/CAD": "USDCAD=X",
+    # Indices
+    "SP500": "^GSPC", "S&P500": "^GSPC", "S&P 500": "^GSPC",
+    "NASDAQ": "QQQ", "NASDAQ100": "^NDX",
+    "DOW": "DIA", "DOW JONES": "DIA",
+    "RUSSELL2000": "IWM", "RUSSELL 2000": "IWM",
+}
+
+
+def normalize_ticker(ticker: str) -> str:
+    """Normalize AI-generated ticker strings to valid Yahoo Finance symbols."""
+    if not ticker:
+        return ticker
+    t = ticker.strip()
+    upper = t.upper()
+    # Check alias map (case-insensitive)
+    if upper in TICKER_ALIASES:
+        return TICKER_ALIASES[upper]
+    # Forex: "EUR/USD" style not caught above
+    if "/" in t:
+        parts = t.upper().split("/")
+        if len(parts) == 2 and all(2 <= len(p) <= 4 for p in parts):
+            return parts[0] + parts[1] + "=X"
+    return t
+
+
 _TICKER_ASSET_CLASS: dict = {
     # Energy
     "CL=F": "energy", "BZ=F": "energy", "NG=F": "energy", "RB=F": "energy", "HO=F": "energy",