fix(demo): embed font into svg for consistent rendering

The demo svg was generated with svg-term-cli but I noticed whitespace
inconsistencies on windows. I fixed it by bundling CascadiaMonoPL.ttf
into the svg.

    $ npm i -D git+https://github.com/miraclx/svgembed svg-term-cli
    $ npx svg-term-cli --cast=92UaraAB1LOZR13laURQ5jB7b --out tmp.svg --window
    $ npx svgembed -i tmp.svg -o demo.svg -f CascadiaMonoPL.ttf

Related links:

- https://github.com/marionebl/svg-term-cli
- marionebl/svg-term-cli#61
- https://github.com/miraclx/svgembed