chore: groundwork for media purge system

docs/design/README.md

@@ -34,7 +34,7 @@ The visual spec of record for the back-office SPA and the transactional emails,
 | [Integration](screens/integration.md) | `/integration` | 8 | `source/RenewCMS Screens Back-office.dc.html` |
 | [API keys](screens/integration-api-keys.md) | `/integration/api-keys` | 12 | `source/RenewCMS Screens API keys.dc.html` |
 | [Users](screens/users.md) | `/users` | 17 | `source/RenewCMS Screens Back-office.dc.html` |
-| [Settings](screens/settings.md) | `/settings` | 25 | `source/RenewCMS Screens Back-office.dc.html` |
+| [Settings](screens/settings.md) | `/settings` | 25 | `source/RenewCMS Screens Back-office.dc.html`, `source/RenewCMS Screens Media cleanup.dc.html` |
 | [Profile](screens/profile.md) | `/profile` | 13 | `source/RenewCMS Screens Back-office.dc.html` |
 | [Accept invite](screens/accept-invite.md) | `/invite/accept?c=CODE` | 9 | `source/RenewCMS Screens Auth.dc.html` |
 | [Global](screens/global.md) | `any route` | 4 | `source/RenewCMS Screens Back-office.dc.html` |
@@ -42,6 +42,7 @@ The visual spec of record for the back-office SPA and the transactional emails,
 ## Other boards
 
 - `source/MediaFrame.dc.html`: the frame that draws the Media and Media picker states (the Back-office board imports it). Like `AppFrame.dc.html`, it holds the exact values.
+- `source/SettingsFrame.dc.html`: the Media cleanup card and its purge dialog (the Media cleanup board imports it, with `MediaFrame.dc.html` for the Duplicates toolbar button). They hold the exact values.
 - `source/IntegrationPage.dc.html` and `source/ApiKeysPage.dc.html`: the page components for the Integration and API keys screens (imported by `AppFrame.dc.html`). They hold the exact values.
 - `source/RenewCMS Prototype.dc.html`: the clickable flows (first run, edit and publish, password reset, delete, session expiry mid-edit).
 - `source/RenewCMS Handoff.dc.html`: the handoff page the first markdown here was generated from. It predates the Users and Profile screens and the invitation email, so it does not list them. Those are written by hand from the Back-office board, `AppFrame.dc.html`, the Prototype and `emails/invitation.html`.