fix: storeFact always bumps updated_at; fix $fresh() wrong column name

ON DUPLICATE KEY UPDATE was not touching updated_at, so if a site's
status didn't change MySQL never fired the ON UPDATE trigger and the
row timestamp stayed 6 days stale. do_server.php's 15-min freshness
window then returned empty sites.

Also fixes $fresh() querying WHERE fact_category= (non-existent column)
instead of WHERE category=, which always returned no rows.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/endpoints/facts_collector.php

@@ -23,7 +23,7 @@ function collect_all(): array {
     // Prevents expensive external calls when data is still fresh.
     $fresh = function(string $cat, int $secs): bool {
         $row = JarvisDB::query(
-            'SELECT updated_at FROM kb_facts WHERE fact_category=? ORDER BY updated_at DESC LIMIT 1',
+            'SELECT updated_at FROM kb_facts WHERE category=? ORDER BY updated_at DESC LIMIT 1',
             [$cat]
         );
         if (empty($row[0]['updated_at'])) return false;