Adds two new legendary commanders: "Blood Sovereign" (bt_cmd_2) and "The Hemorrharch" (bt_cmd_3).
Introduces six new cards:
- Common: Bloodsucker (bt_bloodsucker_1)
- Epic: Hemorrhage (bt_hemorrhage_1)
- Rare: Crimson Stalker (bt_crimson_stalker_1)
- Legendary: Crimson Fury (bt_crimson_fury_1), Blood Martyr (bt_blood_martyr_1), Sanguine Bastion (bt_sanguine_bastion_1)
Updates `data/missions.json` to integrate new commanders and cards into opponent rosters for missions 006 through 013, replacing placeholder or previous units to reflect the expanded faction lineup. Includes corresponding card art assets.
