diigo-cache: date windows and search on the public page (1d)

/public/<username> takes days, after, before, in (year, month,
quarter, ISO week), by=updated|created, and q (words, "phrases",
#tags, -negation, gmail/Slack/GitHub date operators). JSON answers
echo the parsed filter; a malformed one is a 400.

Filters query the stored items in sqlite through the read-only
viewer instead of walking diigo pages: the public page keeps no
fetch authority, and a filled cache already holds every item.
Results say `complete` when every diigo page is stored; freshness
is 1f's head refresh. So the fetch budget and the O(log pages)
walk test go, and the fake deep account shrinks to 300.

Generated-by: Claude Opus 5.5

diigo-cache/src/cache-read.sql

@@ -19,3 +19,14 @@ where cast(items.updated as integer) >= ?;
 
 -- pagesThrough:
 select count(*) as n from pages where page_num <= ?;
+
+-- itemsByUpdated:
+select json from items
+where cast(updated as integer) >= ? and cast(updated as integer) < ?
+order by cast(updated as integer) desc, item_id;
+
+-- itemsByCreated:
+select json from items
+where cast(json_extract(json, '$.created_at') as integer) >= ?
+	and cast(json_extract(json, '$.created_at') as integer) < ?
+order by cast(json_extract(json, '$.created_at') as integer) desc, item_id;