Add QK-norm toggle, TinyStories prep and automatic run logging

nanoGPT gets a qk_norm flag (off = upstream behaviour), a seed option and
a resolved-config dump. run.py logs each run's git commit, config, data
checksums, environment and metrics, and stops diverged runs.

Claude-Session: https://claude.ai/code/session_01S8KN7NuUCm8nXLmy6eDuVv

06-experiments/requirements.txt

@@ -0,0 +1,19 @@
+# exact versions used for the tech spike (28/10/2026); install with: uv venv --python 3.12 .venv && uv pip install -r requirements.txt
+certifi==2026.10.23
+charset-normalizer==3.5.2
+filelock==4.2.4
+fsspec==2026.9.0
+idna==3.20
+jinja2==3.1.6
+markupsafe==3.0.4
+mpmath==1.3.0
+networkx==3.7
+numpy==2.5.4
+regex==2026.9.29
+requests==2.34.2
+setuptools==84.2.1
+sympy==1.14.0
+tiktoken==0.14.0
+torch==2.15.0
+typing-extensions==4.16.0
+urllib3==2.8.0