chore: groundwork for SEO fixes and tech&vis debt

docs/design/states.md

@@ -51,6 +51,9 @@ Glossary pass 2, changes made: activity log lines "Removed N expired invites" an
 | 422 bio_too_long | "Shorten the bio to 280 characters." (inline under bio) |
 | 422 invalid_url | "Enter a full URL starting with https://." (inline under website and each social link) |
 | 404 author_not_found | "That author no longer exists" / "It was deleted somewhere else, so we removed it from the list." (info toast) |
+| 404 site_not_found (sitemap) | GET /v1/site/{key}/sitemap, unknown key. The body is the code `site_not_found`, shown on Integration in the code style (not rewritten as prose). |
+| 400 (sitemap page or size) | "The request cannot be processed due to a mismatch in the format of the body." (same text as the other routes on Integration) |
+| 403 owner_only vs article SEO | Integration note under the 403 row: "Site SEO defaults are owner only. Article SEO fields need only the right to edit the article." |
 | 500 – | "Couldn't save the site. Your changes are still here. Try again in a moment." / "Couldn't save the author. Your changes are still here. Try again in a moment." / "Couldn't create the author" / "The article is unchanged. Try again in a moment." (notice inside the panel or dialog) |
 
 ## Public image 400 bodies
@@ -59,6 +62,9 @@ Glossary pass 2, changes made: activity log lines "Removed N expired invites" an
 ## Articles and Media pagination
 Same states and copy on Articles and Media (Media draws them under the grid or list). Loading next page keeps row height, controls disabled, summary "Loading page 7…". Error "Couldn't load page 7. Showing page 6." with Retry. Out of range "That page doesn't exist. Showing the last page." Page size menu offers 5, 25, 50, 100. Invalid `page` or `size` in the URL (size=30, page=abc, page=0) is replaced by the default without a notice; the API 400 never reaches the user.
 
+## Sites and authors pagination
+Groups "Sites: pagination" and "Authors: pagination", 10 states each, same pager as Articles and Media, sizes 5, 25, 50, 100 (default 25). First, middle and last page; single page (count line "N sites" or "N authors" only, no pager, no size select); page-size menu; loading ("Loading page N…", skeleton rows, pager kept and disabled); error ("Couldn't load page N. Showing page M." with Retry, rows and page number kept); empty after search (existing empty state, no pager); search resets to page 1; long labels on mobile. Out of range: ?page past the end is replaced by the last page, with "That page doesn't exist. Showing the last page." (not drawn; as Articles). Details in screens/sites.md and screens/authors.md.
+
 ## Editor
 Counter without limit ("1,204 words · 7,318 characters"; at 120,000 characters "19,845 words · 120,000 characters"), "Saving…", "Saved", "Couldn't save. Your text is kept. Retry". Link states and the toolbar overflow are drawn in the Editor group (11 states).