The DB-backed HotMemory.read() dropped the "> Last updated:" header
that the old file-based template included. This meant callers saw no
indication of when hot memory was last computed, and the stale-file
problem (#10) had no equivalent fix in the new code path.
Add the current UTC timestamp to the computed output so the timestamp
is always fresh — never stale from a persisted file.
Fixes#1339
Refs #10
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
