Change Set 3: Debris With Weight

Salvage stopped being disposable and started carrying real physics.

• Garbage clumps now carry real mass and size. A big wad is a slow, heavy anchor that loose pieces fall into.
• A single shot shatters a clump back into individual pickups.
• Salvage is now permanent. It leaves the field exactly two ways: you recycle it, or it becomes a Hunter. The garbage economy is a closed loop.