feat(memory): add automated nightly consolidation at 4:00 AM UTC

Step 2 of memory system overhaul: automated scheduling.

- New consolidation_scheduler.py: run_nightly_consolidation() function that
  checks Cat health, triggers consolidation via WebSocket, and tracks
  run history with success/failure stats
- bot.py on_ready: register APScheduler cron job (hour=4, minute=0)
  alongside the existing daily DM analysis job
- routes/memory.py: expose consolidation status (last_run, last_result,
  last_error, is_running, total_runs, successful_runs) in the
  /memory/status API response
- Web UI: show consolidation schedule info (last run time, success/fail,
  run counts) below the manual consolidate button, with 'running now'
  indicator when active

The 'sleep consolidation' metaphor is now actually automated instead of
being manual-only.

bot/static/index.html

@@ -1034,6 +1034,7 @@
           <h4 style="margin: 0 0 0.5rem 0;">🌙 Memory Consolidation</h4>
           <p style="color: #aaa; font-size: 0.85rem; margin-bottom: 0.75rem;">
             Trigger the sleep consolidation process: analyzes episodic memories, extracts important facts, and removes trivial entries.
+            <br><span style="color: #888;">⏰ Scheduled nightly at 4:00 AM UTC</span>
           </p>
           <div style="display: flex; gap: 0.5rem; align-items: center;">
             <button id="consolidate-btn" onclick="triggerConsolidation()" style="background: #5b3a8c; color: #fff; padding: 0.5rem 1rem; border: none; border-radius: 4px; cursor: pointer; font-weight: bold;">
@@ -1041,6 +1042,7 @@
             </button>
             <span id="consolidation-status" style="color: #888; font-size: 0.85rem;"></span>
           </div>
+          <div id="consolidation-schedule-info" style="margin-top: 0.5rem; color: #666; font-size: 0.78rem;"></div>
           <div id="consolidation-result" style="display: none; margin-top: 0.75rem; background: #111; border: 1px solid #333; border-radius: 4px; padding: 0.75rem; font-size: 0.85rem; color: #ccc; white-space: pre-wrap; max-height: 200px; overflow-y: auto;"></div>
         </div>