fix(archive): keep the Moved to Archive toast off the next events

Centred at the bottom for eight seconds, the Undo toast sat over the
events moving up into the gap an ignored or completed row left. It now
sits in the bottom-right corner, lasts four seconds, and has an OK that
closes it without undoing. On a phone there is no side to clear and the
bottom is where an event's page ends, so it goes to the top, over the
header.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/DESIGN.md

@@ -496,7 +496,12 @@ text. On focus the border moves to faint. The field gets no glow, because a form
 - **Detail sheet:** `surface` fill with a hairline border and 16px corners. It rises from the bottom
   on a phone, is centred at `max-w-lg` from `sm` up, and sits over the scrim.
 - **Toast / update notice:** `raised` fill, hairline border, 12px corners and the only shadow in the
-  system. Each offers one action.
+  system. Each offers one action, and the "Moved to Archive" toast also a plain OK that only closes
+  it. That toast sits in the bottom-right corner, 24px in, at most 420px wide, so it stays off the
+  reading column and the events moving up into the gap; up to 700px wide there is no side to clear,
+  so it spans the width 16px in from each edge at the top, over the header, because at the bottom it
+  covered the end of an event's page opened while it was up. It was centred, for eight seconds,
+  until 2026-11-10, when the owner found it covering the next events.
 
 ### Daily burst
 A small spray of 3px sparks that fires once, in the row, when a reader finishes one thing: a daily

docs/PRD.md

@@ -193,7 +193,8 @@ the cut are still counted in the header, still on the timeline, and one tap away
 **F3 — Mark completed.**
 Done writes durable progress and a metadata snapshot immediately. A confirmation remains for about
 0.9 seconds (1.5 until 2026-10-20, which read as unresponsive) before the row fades/collapses into
-Archive. Undo is available for eight seconds; Archive Restore remains available afterwards. A failed
+Archive. Undo is offered in a toast, out of the list's way, for four seconds (eight until 2026-11-10, when it sat
+over the next events), and its OK closes it sooner; Archive Restore remains available afterwards. A failed
 write is disclosed and never presented as saved. Reduced motion removes the fade.
 
 **F4 — Settings and visibility.**