feat: add data/ skeleton for portable model setup

Add gitignored data/ directory with .gitkeep structure so anyone
cloning the repo knows exactly where to place model weights and
kernels. Configs now use repo-relative paths — symlink or populate
data/ locally.

  data/models/gemma3/27b/   ← model weights
  data/models/gemma3/1b/    ← lightweight model
  data/safetensors/gemma-3/ ← raw checkpoints
  data/kernels/             ← LEK kernel files

Co-Authored-By: Virgil <virgil@lethean.io>

.core/ai/models/gemma3/1b.yaml

@@ -8,9 +8,9 @@ parameters: 1b
 format: safetensors
 
 paths:
-  base: /Volumes/Data/lem/gemma-3-1b-it-base
+  base: data/models/gemma3/1b
 
-kernel: /Volumes/Data/lem/lek-1-kernel.txt
+kernel: data/kernels/lek-1-kernel.txt
 training: training/lem/model/gemma3/1b
 
 lessons:

.core/ai/models/gemma3/27b.yaml

@@ -7,13 +7,13 @@ family: gemma3
 parameters: 27b
 format: safetensors
 
-# Model paths (absolute — these are large files on external storage).
+# Model paths (relative to repo root — symlink or populate data/).
 paths:
-  base: /Volumes/Data/lem/gemma-3-27b-it-base
-  safetensors: /Volumes/Data/lem/safetensors/gemma-3/
+  base: data/models/gemma3/27b
+  safetensors: data/safetensors/gemma-3/
 
 # Kernel (system prompt for LEK-aligned generation).
-kernel: /Volumes/Data/lem/lek-1-kernel.txt
+kernel: data/kernels/lek-1-kernel.txt
 
 # Training data root.
 training: training/lem/model/gemma3/27b

data/.gitignore

@@ -0,0 +1,12 @@
+# Ignore all model weights, safetensors, and kernel files.
+# These are large and should be downloaded or symlinked locally.
+#
+# Structure:
+#   data/models/gemma3/27b/   ← model weights (safetensors, config.json, etc)
+#   data/models/gemma3/1b/    ← lightweight model
+#   data/safetensors/gemma-3/ ← raw safetensors checkpoints
+#   data/kernels/             ← LEK kernel files (.txt)
+
+*
+!.gitignore
+!**/.gitkeep