fix: restore live timestamp to HotMemory.read() output

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>

src/timmy/memory/consolidation.py

@@ -89,7 +89,12 @@ class HotMemory:
         """Read hot memory — computed view of top facts + last reflection from DB."""
         try:
             facts = recall_personal_facts()
-            lines = ["# Timmy Hot Memory\n"]
+            now = datetime.now(UTC).strftime("%Y-%m-%d %H:%M UTC")
+            lines = [
+                "# Timmy Hot Memory\n",
+                f"> Working RAM — always loaded, ~300 lines max, pruned monthly",
+                f"> Last updated: {now}\n",
+            ]
 
             if facts:
                 lines.append("## Known Facts\n")