fix: parse SQLite timestamps as UTC, not local time

SQLite datetime('now') returns 'YYYY-MM-DD HH:MM:SS' with no timezone
marker. JS was treating this as local time, so timestamps showed the
correct UTC digits but with the local TZ abbreviation attached (e.g.
'7:15 PM EDT' when the real local time was '3:15 PM EDT').

Add parseUtc() which appends 'Z' before parsing any string that has no
existing timezone marker, ensuring JS always treats them as UTC before
the display-timezone conversion is applied.

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

js/ui.js

@@ -39,17 +39,25 @@ function esc(str) {
   return d.innerHTML;
 }
 
+// SQLite datetime('now') → 'YYYY-MM-DD HH:MM:SS' (UTC, no timezone marker).
+// Appending 'Z' tells JS to parse it as UTC rather than local time.
+function parseUtc(d) {
+  if (typeof d !== 'string') return new Date(d);
+  const hasZone = d.endsWith('Z') || /[+-]\d{2}:\d{2}$/.test(d);
+  return new Date(hasZone ? d : d.replace(' ', 'T') + 'Z');
+}
+
 function fmtDate(d) {
   if (!d) return '—';
   try {
-    return new Date(d).toLocaleDateString('en-US', { year: 'numeric', month: 'short', day: 'numeric', timeZone: getTimezone() });
+    return parseUtc(d).toLocaleDateString('en-US', { year: 'numeric', month: 'short', day: 'numeric', timeZone: getTimezone() });
   } catch (e) { return d; }
 }
 
 function fmtDateFull(d) {
   if (!d) return '—';
   try {
-    return new Date(d).toLocaleString('en-US', { year: 'numeric', month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit', timeZone: getTimezone(), timeZoneName: 'short' });
+    return parseUtc(d).toLocaleString('en-US', { year: 'numeric', month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit', timeZone: getTimezone(), timeZoneName: 'short' });
   } catch (e) { return d; }
 }