feat(media): pagination

docs/design/screens/media.md

@@ -1,6 +1,6 @@
 # Media
 
-Route: `/media`, `/media (detail panel)`, `/media?filter=duplicates`. API: GET /v1/media/ · POST /v1/media/ · PATCH /v1/media/{id} · DELETE /v1/media/{id} · POST /v1/media/merge · GET /v1/media/{id}/usage · GET /v1/media?variants=with|without&sort=total_size · GET /v1/media/{id}/variants · POST /v1/media/{id}/variants/{name} · DELETE /v1/media/{id}/variants/{name} · owner and admin only.
+Route: `/media`, `/media?page=7&size=50`, `/media (detail panel)`, `/media?filter=duplicates`. API: GET /v1/media/?page=&size=&q=&filter= (total in `X-Total-Count`) · POST /v1/media/ · PATCH /v1/media/{id} · DELETE /v1/media/{id} · POST /v1/media/merge · GET /v1/media/{id}/usage · GET /v1/media?variants=with|without&sort=total_size · GET /v1/media/{id}/variants · POST /v1/media/{id}/variants/{name} · DELETE /v1/media/{id}/variants/{name} · owner and admin only.
 
 New route for verified users, in the sidebar between Articles and Users with the images icon. Images belong to the library, not to an article: one image can be used in many articles, and deleting an article never deletes images. Uploads from this page are not cropped or resized, and the file is stored as chosen. "Used in" is read from article bodies each time the list loads. Duplicates are images with identical content, whatever their filenames. Alt text is not stored on the image; it is set when inserting into an article. Search, filter, sort and view are stored in the query string. Keyboard: grid items are buttons in one tab stop each; Enter opens the detail panel, Space toggles selection, and Escape closes the panel or clears the selection. Selection changes are announced ("north-wall.jpg selected, 1 selected").
 
@@ -10,7 +10,7 @@ Visual reference: `RenewCMS Screens Back-office.dc.html`, groups "Media", "Media
 
 Every state below is drawn in light and dark (theme switch on the board), at 1440×900 and 390×844 (both frames sit side by side). Board: `RenewCMS Screens Back-office.dc.html`. Copy is exact; where a cell is empty the state reuses the fixed copy.
 
-### Media (group "Media", 43 states)
+### Media (group "Media", 52 states)
 
 Route: `/media`. API: GET /v1/media/ · POST /v1/media/ · PATCH /v1/media/{id} · DELETE /v1/media/{id} · POST /v1/media/merge · GET /v1/media/{id}/usage.
 
@@ -18,7 +18,7 @@ New route for verified users, in the sidebar between Articles and Users with the
 
 | # | State | Trigger | Copy |
 |---|---|---|---|
-| 1 | Grid, many images | Default view. 12 images, newest first. Each item is a button labelled like "north-wall.jpg, 3.9 MB, used in 2 articles". Badges: "Unused" (warm), "Duplicate" (info), "Used in N" (outline). The Duplicates tab carries a count of groups only while duplicates exist. |  |
+| 1 | Grid, many images | Default view. 12 images, newest first. Each item is a button labelled like "north-wall.jpg, 3.9 MB, used in 2 articles". Badges: "Unused" (warm), "Duplicate" (info), "Used in N" (outline). The Duplicates tab carries a count of groups only while duplicates exist. Below the grid: "Showing 1–12 of 12" and the page-size select (same paginator as Articles). |  |
 | 2 | Grid, few images | Three images. Cards keep their size instead of stretching. Checkerboard shows behind the SVG. |  |
 | 3 | List view | The list icon in the toggle. A table from md up (Filename, Dimensions, Size, Type, Used in, Uploaded by, Uploaded) and a card list below md. The "Used in" count opens the article list in the detail panel. |  |
 | 4 | Loading | The first load, a retry, or a change of search or filter. Skeleton cards appear after 150 ms. |  |
@@ -61,6 +61,15 @@ New route for verified users, in the sidebar between Articles and Users with the
 | 41 | Merge: done | 200: the group leaves the list. When it was the last one, "No duplicates" shows. | "Copies merged" / "2 copies merged. 5 articles updated." |
 | 42 | List failed to load | A 500 or network failure on the list request. The alert replaces the images; Try again repeats the request. |  |
 | 43 | Offline | navigator.onLine is false. Loaded images stay browsable. Upload, Rename, Delete and Merge are disabled, and the banner says why. |  |
+| 44 | Pagination: first page | /media. Previous and First are disabled. Summary "Showing 1–25 of 312". The paginator sits under the grid or list and uses the Articles controls: 5, 25, 50 or 100 per page, default 25; page and size live in the URL as page and size (/media?page=7&size=50); search, tab, sort, view and size changes reset to page 1. API: GET /v1/media/?page=&size=&q=&filter= with the total in X-Total-Count. |  |
+| 45 | Pagination: middle page | /media?page=7. Current page uses --rc-sand and --rc-on-sand; ellipses mark skipped ranges. |  |
+| 46 | Pagination: last page | /media?page=13. Next and Last are disabled. Summary "Showing 301–312 of 312". |  |
+| 47 | Pagination: list view | Same paginator under the table. On mobile: Previous, "Page 2 of 13", Next, with the 44 px targets. |  |
+| 48 | Pagination: loading next page | Next was pressed. Skeleton cards keep the grid height, controls are disabled, summary reads "Loading page 7…". |  |
+| 49 | Pagination: error loading a page | 500 or network failure on page change. Previous images stay; Retry sits in the notice. | "Couldn't load page 7. Showing page 6." |
+| 50 | Pagination: page out of range | /media?page=99 is replaced with ?page=13 and this notice is shown. | "That page doesn't exist. Showing the last page." |
+| 51 | Pagination: page size menu | The select opens upward. 5, 25, 50 or 100; the chosen size is saved as size and the page resets to 1. |  |
+| 52 | Pagination: focus-visible | Keyboard focus on Next: 2 px --ui-primary outline, 2 px offset. Same ring on every paginator control. |  |
 
 ### 3. Media library (group "Media library", 6 states)