Stop loading the bold face the editor never draws in (#273)

The editor waits for every face in FACES before it starts. Source Sans 3
in 700 was one of them, but nothing in src/ sets a weight above 600, so
it cost a download and a wait for nothing.

- fonts.ts loads Source Sans 3 in 400, 500 and 600 plus Source Code Pro
  400. The 700 file (15 596 bytes) is gone from src/ui/fonts.
- A search for bold, font-weight and HTML headings in src/, web/*.html
  and the player found nothing that would fall back to 700.
- fonts.test.ts now checks both ways. A loaded Sans face must be set
  somewhere in src/, and every .woff2 in the font folder must be in
  FACES, so a stray file the glyph test would still read shows up too.
- The weight scan moved into usedWeights(), since two tests need it.

Tests:
- Gate on melektaus-atx: 197 files, 2856 tests (2855 + 1), exit 0.
- e2e 1-14: all passed, 492 checks, loaded faces ["400","500","600"].
- e2e 14 alone fails its two tab width checks, as known: it needs the
  documents 7-13 open. The font check was green there as well.
- dist/assets holds no 700 file after the build.
- Counter check: loading 700 again with its file fails the new
  "loads no face the editor never sets".
- Counter check: the file back without a FACES entry fails
  "... and no other" and names the file.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui/fonts.ts

@@ -2,13 +2,11 @@ import codePro400 from './fonts/source-code-pro-latin-400-normal.woff2?url';
 import sans400 from './fonts/source-sans-3-latin-400-normal.woff2?url';
 import sans500 from './fonts/source-sans-3-latin-500-normal.woff2?url';
 import sans600 from './fonts/source-sans-3-latin-600-normal.woff2?url';
-import sans700 from './fonts/source-sans-3-latin-700-normal.woff2?url';
 
 export const FACES: readonly [family: string, url: string, weight: string][] = [
   ['Source Sans 3', sans400, '400'],
   ['Source Sans 3', sans500, '500'],
   ['Source Sans 3', sans600, '600'],
-  ['Source Sans 3', sans700, '700'],
   ['Source Code Pro', codePro400, '400'],
 ];
 

tests/ui/fonts.test.ts

@@ -97,27 +97,45 @@ function codePoints(file: string): Set<number> {
   return found;
 }
 
-describe('editor fonts', () => {
-  it('loads a face for every weight the editor sets (#214)', () => {
-    const loaded = new Set(
-      FACES.filter(([family]) => family === 'Source Sans 3').map(([, , weight]) => weight),
-    );
+/** The weights `src/` sets as `fontWeight`, plus the 400 a style without one draws in. */
+function usedWeights(): Set<string> {
   const used = new Set(['400']);
   for (const file of sources('src'))
     for (const [, setting] of readFileSync(file, 'utf8').matchAll(/fontWeight:([^,\n}]*)/g))
       for (const [, weight] of setting!.matchAll(/'(\d{3}|bold|normal)'/g))
         used.add(weight === 'bold' ? '700' : weight === 'normal' ? '400' : weight!);
+  return used;
+}
+
+describe('editor fonts', () => {
+  const loaded = new Set(
+    FACES.filter(([family]) => family === 'Source Sans 3').map(([, , weight]) => weight),
+  );
+
+  it('loads a face for every weight the editor sets (#214)', () => {
+    const used = usedWeights();
     expect(used.has('500')).toBe(true);
     for (const weight of used) expect(loaded, `weight ${weight}`).toContain(weight);
   });
 
-  it('ships a file for every face it loads', () => {
-    const files = readdirSync(FONT_DIR);
+  // Every face is waited for before the editor starts (#273).
+  it('loads no face the editor never sets', () => {
+    const used = usedWeights();
+    for (const weight of loaded) expect(used, `weight ${weight}`).toContain(weight);
+  });
+
+  it('ships a file for every face it loads, and no other', () => {
+    const files = readdirSync(FONT_DIR).filter((f) => f.endsWith('.woff2'));
     for (const [, url, weight] of FACES)
       expect(
         files.some((f) => url.endsWith(f)),
         `${url} (${weight})`,
       ).toBe(true);
+    for (const file of files)
+      expect(
+        FACES.some(([, url]) => url.endsWith(file)),
+        file,
+      ).toBe(true);
   });
 
   it('reads the Latin subset from the files themselves', () => {