tags/stats, tags/{tag}/prompts and tags/filter parsed limit/offset with a
bare int(), so limit=999999 was passed straight to SQLite and a huge
offset raised OverflowError (500). They now share parse_page_params
(limit 1..500, offset 0..MAX_PAGE_OFFSET, 400 on non-integers), and
/recent clamps the offset it derives from ?page= the same way.