docs: add music credits and descope notes

Only the scroller text credited ride.mod; add CREDITS.md and a
semantic-fallback line so no-JS visitors also see the "11th-hour"
by TDK CC BY 4.0 attribution (The Mod Archive, unmodified).

Also record the two spec items descoped during implementation:
chunky-pixel retro look instead of ordered dithering, and a
single MOD track instead of per-stop ambience shifts.

CREDITS.md

@@ -0,0 +1,9 @@
+# Credits
+
+## Music
+
+**"11th-hour"** by TDK
+
+- Source: [The Mod Archive, module id 67104](https://modarchive.org/index.php?request=view_by_moduleid&query=67104)
+- License: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/)
+- Used unmodified.

docs/superpowers/specs/2026-07-09-clement-saillant-cc-design.md

@@ -141,3 +141,10 @@ board and alight at stops like passengers.
 - Final bio text + pixel-art avatar.
 - Greetings list content.
 - MOD module choice (original Électron Fou chiptune vs licensed module).
+
+## Descoped (2026-07-09)
+
+- Ordered-dithering post-process was replaced by low-dpr chunky pixels —
+  an equivalent retro effect with zero added dependencies.
+- Per-stop audio ambience shift at the Électron Fou stop was deferred;
+  a single MOD track ships for the whole ride instead.

src/content/music.ts

@@ -4,3 +4,10 @@ export const MUSIC = {
   listenLabel: 'Écouter sur Bandcamp',
   listenUrl: 'https://lelectron-fou.bandcamp.com',
 }
+
+// Attribution for the background MOD track (public/music/ride.mod),
+// "11th-hour" by TDK, CC BY 4.0, from The Mod Archive. Kept HTML-free
+// here so it stays a pure string; src/fallback/inject.ts wraps it with
+// the license/source links for the semantic fallback markup.
+export const MUSIC_CREDIT =
+  'Musique : « 11th-hour » par TDK — CC BY 4.0, The Mod Archive.'

src/fallback/inject.test.ts

@@ -20,4 +20,12 @@ describe('renderFallbackHtml', () => {
     const out = renderFallbackHtml(template)
     expect(out).not.toMatch(/<!--(nav|bio|music|greetings|name|tagline)-->/)
   })
+  it('credits the ride.mod track with a CC BY 4.0 link', () => {
+    const out = renderFallbackHtml(template)
+    expect(out).toContain(
+      '<p class="muted">Musique : « 11th-hour » par TDK — ' +
+        '<a href="https://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a>, ' +
+        '<a href="https://modarchive.org/index.php?request=view_by_moduleid&amp;query=67104">The Mod Archive</a>.</p>',
+    )
+  })
 })

src/fallback/inject.ts

@@ -1,7 +1,25 @@
 import { BIO_LINES, NAME, TAGLINE } from '../content/bio'
 import { GREETINGS } from '../content/greetings'
 import { LINKS } from '../content/links'
-import { MUSIC } from '../content/music'
+import { MUSIC, MUSIC_CREDIT } from '../content/music'
+
+// MUSIC_CREDIT is a plain, HTML-free sentence (see content/music.ts); wrap
+// its two attribution terms with the license and source links here so the
+// content module stays free of markup.
+const MUSIC_CREDIT_LICENSE_URL = 'https://creativecommons.org/licenses/by/4.0/'
+const MUSIC_CREDIT_SOURCE_URL =
+  'https://modarchive.org/index.php?request=view_by_moduleid&query=67104'
+
+function renderMusicCredit(): string {
+  const html = MUSIC_CREDIT.replace(
+    'CC BY 4.0',
+    `<a href="${MUSIC_CREDIT_LICENSE_URL}">CC BY 4.0</a>`,
+  ).replace(
+    'The Mod Archive',
+    `<a href="${MUSIC_CREDIT_SOURCE_URL}">The Mod Archive</a>`,
+  )
+  return `<p class="muted">${html}</p>`
+}
 
 export function renderFallbackHtml(html: string): string {
   const nav = LINKS.map(
@@ -11,7 +29,8 @@ export function renderFallbackHtml(html: string): string {
   const bio = BIO_LINES.map((line) => `<p>${line}</p>`).join('\n        ')
   const music =
     `<h2>${MUSIC.title}</h2><p>${MUSIC.blurb}</p>` +
-    `<p><a href="${MUSIC.listenUrl}">${MUSIC.listenLabel}</a></p>`
+    `<p><a href="${MUSIC.listenUrl}">${MUSIC.listenLabel}</a></p>` +
+    renderMusicCredit()
   const greetings = `<p>Greetings to ${GREETINGS.join(', ')}.</p>`
   return html
     .replace('<!--name-->', NAME)