Add analysis scripts and experiment configurations for bridge attention and sensitivity studies

- Introduced `bridge_attention_ceiling_check.py` for variance decomposition analysis on bridge attention configurations.
- Added `bridge_attention_readout.py` to perform per-tower gate and contribution readouts, including AUC sanity checks.
- Created multiple JSON configuration files for backbone replication experiments, including anonymous CV variants and basic backbones.
- Implemented sensitivity experiments to evaluate the impact of axial length inclusion and EfficientNetV2-M performance at higher resolutions.
- Added a memory probe script to assess GPU memory usage during training with EfficientNetV2-M.

v4/scripts/experiments/backbone_replication/basic_backbones.json

@@ -0,0 +1,46 @@
+[
+  {
+    "_note": "F2 block 1 — basic backbones, ImageNet pretrained, image-only, single-eye, patient-grouped 5-fold CV. VGG16. Replicates v3 phase 1 imageonly_vgg16 in the v4 pipeline.",
+    "run_name": "experiments/backbone_replication/basic_vgg16",
+    "reps": 10,
+    "tower_overrides": {
+      "img": { "args": { "backbone": "vgg16", "freeze_ratio": 0.0 } }
+    }
+  },
+
+  {
+    "_note": "F2 block 1 — MobileNetV2 (ImageNet, img-only, single-eye).",
+    "run_name": "experiments/backbone_replication/basic_mobilenet_v2",
+    "reps": 10,
+    "tower_overrides": {
+      "img": { "args": { "backbone": "mobilenet_v2", "freeze_ratio": 0.0 } }
+    }
+  },
+
+  {
+    "_note": "F2 block 1 — DenseNet121 (ImageNet, img-only, single-eye).",
+    "run_name": "experiments/backbone_replication/basic_densenet121",
+    "reps": 10,
+    "tower_overrides": {
+      "img": { "args": { "backbone": "densenet121", "freeze_ratio": 0.0 } }
+    }
+  },
+
+  {
+    "_note": "F2 block 1 — InceptionV3 (ImageNet, img-only, single-eye). NB: Inception expects 299x299 input — backbone_transform_config auto-overrides crop_size to 299 for inception_v3.",
+    "run_name": "experiments/backbone_replication/basic_inception_v3",
+    "reps": 10,
+    "tower_overrides": {
+      "img": { "args": { "backbone": "inception_v3", "freeze_ratio": 0.0 } }
+    }
+  },
+
+  {
+    "_note": "F2 block 1 — ResNet50 ImageNet-pretrained (the unfrozen ImageNet R50, not refugelike). Anchor for the basic-backbone comparison.",
+    "run_name": "experiments/backbone_replication/basic_resnet50",
+    "reps": 10,
+    "tower_overrides": {
+      "img": { "args": { "backbone": "resnet50", "freeze_ratio": 0.0 } }
+    }
+  }
+]