feat: harden governed PyTorch training programme

docs/AI_PIPELINES.md

@@ -1,5 +1,14 @@
 # AI Pipelines
 
+The cross-task PyTorch scope, capability matrix and national promotion waves are
+defined in `docs/PYTORCH_MODEL_PROGRAM.md`. PyTorch is used only for trainable
+imagery tasks; authoritative GIS measurements remain source-derived. The
+single-class tile exporter accepts explicit `--class-name`,
+`--reference-source` and `--reference-layer` bindings and persists them in its
+evidence summary. Production Tower training uses `TRAIN_DEVICE=cuda:0` with
+`TRAIN_REQUIRE_CUDA=true`, which fails closed without CUDA and records the
+PyTorch/CUDA runtime in `training_summary.json`.
+
 ## 1. Object Detection Pipeline
 
 ```text