2D ASMR Slime: Non-Newtonian Stretch Simulator

This 2D canvas version renders the same viscoelastic stretch-and-relax mechanic as the 3D ASMR slime — a soft blob held together by a ring of damped springs — but exposes the physics you can't see in the 3D toy: real slime's viscosity is not a fixed number, it changes with how fast you deform it. Drag the blob to stretch it and watch it relax back; adjust elasticity and base viscosity like a normal spring-damper, then push the shear-response slider positive for shear-thickening behavior (fast pulls feel stiff, slow pulls ooze) or negative for shear-thinning (fast flicks flow more easily, slow stress feels thick), with a live readout of the current shear rate and effective viscosity multiplier so the cause and effect are never hidden.