Scheduled posts: written now, published at their time

POST /api/v1/statuses with scheduled_at no longer posts at once: the post is
kept as asked (at least five minutes ahead; 300 waiting, 25 a day, as
Mastodon allows), its media kept from the janitor, and a PublishScheduled job
publishes it at its time as the persona. scheduled_statuses lists, moves and
drops them; a moved post's old job finds it not due. Idempotency-Key holds
for scheduling too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

docs/ROADMAP.md

@@ -68,6 +68,9 @@ Written 2026-10-01 from the original 2023 code, the decePubClient UI, a federati
     persona's own and never federate.
   - [x] Filters: v2 (keywords, whole words, statuses, contexts, warn/hide/blur, expiry) and v1 over their keywords;
     every status carries the filters it matches in `filtered`, and clients apply context and action, as Mastodon's do.
+  - [x] Scheduled posts: `scheduled_at` (at least five minutes ahead; 300 waiting, 25 a day) keeps the post as asked,
+    with its media kept from the janitor, and a `PublishScheduled` job publishes it at its time; `scheduled_statuses`
+    lists, moves and drops them.
 
 ## Intent
 
@@ -453,6 +456,7 @@ The first refactor commit is a pure move with namespaces only. Logic changes fol
     `resolve`.
   - **Lists:** CRUD, `:id/accounts`, `accounts/:id/lists`, `timelines/list/:id` (P9).
   - **Filters:** v2 with keywords and statuses, v1, `filtered` on statuses (P9).
+  - **Scheduled statuses:** `scheduled_at` on posting, `scheduled_statuses` (P9).
   - **Stubs:** `custom_emojis`, announcements, trends, suggestions, `followed_tags`, preferences.
 - **Mapping:**
   - Avatar, ForeignAvatar and Group all map to Account (`group: true` for groups). `acct` uses a WebFinger-verified