optimise fonts

fonts are now loaded in a hierarchy:
- title: smallest, loads first, "riki's fluffy little house" characters only
- crit: loads next, contains ASCII + some other stuff, in weights 400-900 (for body text and headings)
- full: loads last, contains everything (italics & monospace too)

static/css/page/tairu.css

@@ -31,6 +31,7 @@
     & .south,
     & .west,
     & .north {
+        font-family: var(--font-code);
         font-weight: 900;
         font-style: normal;
         --recursive-mono: 1;
@@ -108,6 +109,7 @@
 
 .tileset-four-to-eight-demo th-bc {
     & .directions-square {
+        font-family: var(--font-code);
         font-weight: 900;
         font-style: normal;
         --recursive-mono: 1;