* fix: update dart-sass to 1.81.0, enhance makefile performance

use @use instead of @import
update dart-sass to 1.81.0
modify the makefile to enable more efficient concurrent builds

* fix: update ci yaml, add symbolic link from sass to dart-sass

* fix: rm dev-build on push to dev/**

* feat: Modify and footnote superscript styles to match LaTeX theme

Remove footnote superscript background and padding; adjust brackets and spacing of footnote labels

* feat: Superscript footnotes in the text with "[ ]"

* feat: adjust spacing between consecutive footnotes

* feat: align footnote numbers and the indented annotation text

* feat: apply style to exported pdf

* chore: add comments

---------

Co-authored-by: Keldos <hi@keldos.me>
Co-authored-by: RalXYZ <RalXYZ@proton.me>

* fix: fix incorrect numbering of headers when exporting HTML

* fix: use `counter-reset` to create toc counter at first place