refactor: 将子模块转为普通目录，移除外部 git 依赖

- 移除 JEPA/lejepa-identifiability 子模块 gitlink
- 移除 research/multiply/MultiPLY 子模块 gitlink
- 删除 .gitmodules（不再有外部 URL 依赖）
- 两个目录内容作为普通文件纳入主仓库追踪
- 删除各自内部 .git 目录，消除嵌套 git 仓库

JEPA/lejepa-identifiability/experiments/configs/scaling.yaml

@@ -0,0 +1,36 @@
+# Scaling experiment (paper figure)
+# python run.py --config configs/scaling.yaml --N 16 --seed 0
+# python run.py --config configs/scaling.yaml --N 16 --seed 0 --mode infonce
+# python run.py --config configs/scaling.yaml --N 16 --seed 0 --mode whiten
+
+experiment: scaling
+out: results/scaling
+
+# Data
+source_dist: gaussian
+num_eval: 10000
+
+# Training (shared)
+steps: 20000
+lr: 3.0e-3
+batch_size: 256
+rho: 0.95
+log_every: 500
+
+# Encoder
+encoder: matched
+n_layers: 4
+mode: lejepa     # default; override with --mode
+
+# Mode-specific defaults (used based on --mode)
+lamb: 1.0e-6     # for lejepa
+lamb_whiten: 0.5  # used when mode=whiten
+sigma: 1.0       # for infonce
+
+# Mixing
+mixing: coupling
+
+# Sweep dimensions
+dims: [2, 4, 8, 16, 32, 64, 128, 256, 512, 1024]
+seeds: [0, 1, 2, 3, 4]
+K: 3  # parallel encoder runs per (N, seed); pick lowest loss