- process_shader_job: bind all texture params by name, recurse into nested
shader payloads (depth cap 8), fall back to frame size without inputs
- run_effect: take iterative_input so dropshadow previous_iteration_in works
- merge: actually composite inputs; keyer mask, opacity modulation, math
texture ops and mrg generator layers now bind their textures
- transform distort: real fragment-side inverse-matrix sampling
- time offset / time remap: wire NodeBehavior time adjustment hooks
- plugin: fix first-node identity colliding with unbound sentinel