chore: add toc to mobile dropdown menu single items

chore: refactor sidebar

chore: add single layout for blog

chore: add vscode settings

chore: add blog section

chore: add devcontainer.json

chore: exclude icon from mobile nav

chore: support multiple theme switches

- simplify theme switch implementation using data attributes
- hide theme switch when sidebar is disabled

chore: add theme switch to footer

- enable when sidebar is disabled

chore: add format-date partial