Remove Noto fonts and just use system-ui

Yeah, I don't remember why So Many Years Ago I felt it was important to
use the Droid fonts; I adapted this choice into the Noto fonts when
modernizing the other day, but, tbh, the default system fonts are
probably just a better fit for like. everything we do, and then *not*
downloading MB of font files.

I also feel like a lot of the contexts where we used serif fonts were
like, frankly incidental, based on where we chose `<p>` for semantic
reasons? I don't think any of them actually are made much better by
serifs, I'm okay with just simplifying and dropping that, instead of
looking for a better serif font stack to replace it.

app/assets/stylesheets/_layout.sass

@@ -32,9 +32,6 @@ body
 a[href]
   color: $link-color
 
-p
-  font-family: $text-font
-
 input, button, select
   font:
     family: inherit

app/assets/stylesheets/fonts.css.erb

@@ -15,25 +15,3 @@
   font-style: italic;
   src: local("Delicious"), url("<%= font_path "Delicious-Italic.otf" %>");
 }
-
-@font-face {
-  font-family: "Noto Sans";
-  src: local("Noto Sans"), url("<%= font_path "NotoSans-Variable.ttf" %>");
-}
-
-@font-face {
-  font-family: "Noto Sans";
-  font-style: italic;
-  src: local("Noto Sans"), url("<%= font_path "NotoSans-Italic-Variable.ttf" %>");
-}
-
-@font-face {
-  font-family: "Noto Serif";
-  src: local("Noto Serif"), url("<%= font_path "NotoSerif-Variable.ttf" %>");
-}
-
-@font-face {
-  font-family: "Noto Serif";
-  font-style: italic;
-  src: local("Noto Serif"), url("<%= font_path "NotoSerif-Italic-Variable.ttf" %>");
-}

app/assets/stylesheets/partials/clean/_constants.sass

@@ -18,9 +18,8 @@ $error-color:           #8a1f11
 $error-bg-color:        #fbe3e4
 $error-border-color:    #fbc2c4
 
-$header-font:  Delicious, "Noto Sans", Helvetica, Arial, Verdana, sans-serif
+$header-font:  Delicious, system-ui, sans-serif
-$main-font:    "Noto Sans", Helvetica, Arial, Verdana, sans-serif
+$main-font:    system-ui, sans-serif
-$text-font:    "Noto Serif", Georgia, "Times New Roman", Times, serif
 
 $object-img-size:  80px
 $object-width:     100px