FOXP3 and neoplasm: Tumor acidity destabilizes coatings → corelease of IR‐780 and GITR‐PLGA core; 808 nm NIR activates IR‐780 for synergistic PTT/PDT → immunogenic tumor cell death and DC maturation; GITR‐targeted imatinib blocks STAT3/5–FoxP3 in intratumoral Tregs