target_dim 4→6: adds raw_open (OHLCV) and mid_price_open (MBP-10 best bid/ask midpoint at bar formation) to the targets buffer. Micro-reward now uses real intra-bar move (close - open) / atr instead of close-to-close approximation. Also adds spread cost awareness via |open - mid| penalty. Requires fxcache recomputation. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>