Decisions tab: convert the stamps in ## Ruled to the viewer's clock #1839

Problem

With #1836 the owner ruled that agents write every decisions stamp in UTC (the file template ships _Zone: UTC_, hubs stamp items YYYY-MM-DD HH:mm UTC) and the tab converts to the viewer's clock. Cards already do that. The ## Ruled section is shown as written, so its times (ruled 03:46 UTC, DONE 03:52 UTC) read as UTC to the owner, the one place a human still sees a raw stamp.

Fix (BUGFIX, design decided)

In the read-only ## Ruled rendering, find stamps in the forms resolveStamp reads (full stamps with a zone, and bare times zoned by the file's _Zone: line) and render each as a <time> element in the viewer's local time, the same formats the cards use (STAMP_FORMAT, STAMP_TIME_FORMAT), with the written text as the title. Text that is not a stamp is untouched. The file is never rewritten.

Testing

• View test: a Ruled line carrying 2026-10-19 03:46 UTC renders in the viewer's zone with the raw text as title; a line with no stamp renders unchanged.
• Playwright: screenshot of the Ruled list on a file with UTC stamps.

Origin: owner's ruling on 2026-10-19 (everything in UTC, the UI converts), during the review of PR #1837.