Merge upstream into main

Dependencies

• [2] ZLEPKWDJ fork: capture frontend for a note-taking system
• [3] ELIVOJ4N bugfix: zoom in/out hotkeys
• [4] OTIBCAUJ love2d scaffold
• [5] XSLCFVFH .
• [6] Z4KNS42N to open a file without a terminal, drag it on!
• [7] R6GUSTBY default font size and line-height
• [8] AVTNUQYR basic test-enabled framework
• [9] AJB4LFRB try to maintain a reasonable line width

Change contents

• resurrect zombie in main.lua at line 107
  [4.7]→[3.8:293](∅→∅),[4.7]→[3.8:293](∅→∅)
  + function initialize_font_settings(font_height)

  + Editor_state.font_height = font_height

  + love.graphics.setFont(love.graphics.newFont(Editor_state.font_height))

  + Editor_state.line_height = math.floor(font_height*1.3)

  + Editor_state.em = App.newText(love.graphics.getFont(), 'm')

  + end

  +