Add About page

[genwave-radio]

Migrated from the pre-publish internal tracker (gitea-#269, opened 2026-07-16).

Should have version info, system & station stats, etc.

[genwave-radio]

GET /api/attributions is live (SPEC F169.2, STORY-404, PLAN T419) — the credits feed for this page.

Route: GET /api/attributions. Admin surface (404 while Admin:Enabled=false), Curation policy (needs a logged-in admin session, same as every other admin-plane route).

Shape: { groups: [{ kind, packs: [{ slug, name, attributions: [{ title, creator, sourceUrl, license }] }] }] }. Group order is fixed — jingle-pack, font-pack, voice-pack — packs ordered by slug, empty groups omitted entirely.

Rules worth knowing:

• A jingle pack's CC-BY assets each get their own line (title/creator/sourceUrl/license). Every CC0 asset in that pack collapses to one aggregate line named after the pack, with no creator/source.
• A font pack contributes one line at the pack level (its own license/sourceUrl, no creator).
• A voice pack contributes one line naming the pack, license "Synthetic blend", no creator/source — synthetic voices have no per-voice human credit.
• Security note: a font pack's sourceUrl is not scheme-validated at parse time (unlike a jingle asset's), so render it through an https?: allowlist before ever using it as an href.
  Example body:

{
  "groups": [
    { "kind": "jingle-pack", "packs": [{ "slug": "mixed-credits", "name": "Mixed Credits Pack",
      "attributions": [
        { "title": "Bed One", "creator": "Jane Doe", "sourceUrl": "https://example.com/bed-one", "license": "CC-BY" },
        { "title": "Mixed Credits Pack", "creator": null, "sourceUrl": null, "license": "CC0" }
      ] }] }
  ]
}

Consumer: the About page epic (gh-#16).