v0.7.20

Fixed — nothing leaves your machine, and the Keras demo is a real run

• The dashboard fetched its fonts from Google. Every dashboard, every
  exported HTML report and every VS Code panel requested DM Sans and
  Instrument Serif from fonts.googleapis.com — in a product that says it runs
  locally and sends nothing. Both fonts (SIL OFL 1.1) are bundled now and
  inlined into the stylesheet by every build, so an exported report carries
  its fonts and works offline; the VS Code webview's CSP admits fonts only as
  data: URIs. The browser suite now asserts, in Chromium, Firefox and
  WebKit, that the dashboard makes no request off the machine and that an
  exported report opened with the network cut still draws its own fonts. The
  licence texts ship beside the built dashboard, credited in NOTICE.
• epochix demo keras played a hand-written log. It skipped epochs 6, 7,
  9, 11, 13, 14, 16, 17 and 19, and its model summary was one Keras cannot
  print — a Dense layer straight after a pooling layer, with no Flatten. It is
  now a real run: a small CNN trained on scikit-learn's handwritten digits by
  demo/keras_image_classifier_source.py, every epoch and every number
  (timings included) from the actual optimisation, reproducible with the same
  seed. The README's example follows it.
• The package's copy of the demos was tied to nothing. epochix demo
  plays src/epochix/_demos/, while the README, the tests and the corpus read
  demo/; regenerating one would have left the other playing the old log.
  A test now fails if any packaged demo differs from its original.