Add Incident Postmortem Generator dashboard

Interactive postmortem tool with:
- 4 pre-built incident scenarios (cascade failure, budget blowout, hallucination storm, latency spike)
- Chronological timeline builder with Canvas visualization
- Autonomous root cause analysis (duration, detection gaps, blast radius, communication, pattern matching)
- Auto-generated prioritized action items (P0-P3) based on severity and incident characteristics
- Proactive insights with recommendations trending toward autonomous incident response
- Response completeness scoring
- Export to Markdown, JSON, and standalone HTML report
- Local storage draft save/load
- Dark/light theme support

Usage: Open dashboard/postmortem.html or click Postmortem in the nav bar

Author: sauravbhattacharya001

dashboard/index.html

@@ -31,6 +31,7 @@ <h1 class="logo">🔍 AgentLens</h1>
         <a href="cost-anomaly.html" class="btn btn-alert-header" style="text-decoration:none">🔮 Cost Anomaly</a>
         <a href="topology.html" class="btn btn-alert-header" style="text-decoration:none">🗺️ Topology</a>
         <a href="runbooks.html" class="btn btn-alert-header" style="text-decoration:none">📋 Runbooks</a>
+        <a href="postmortem.html" class="btn btn-alert-header" style="text-decoration:none">🩺 Postmortem</a>
         <button class="btn btn-alert-header" onclick="openAlertsModal()" id="alertsBtn">
           🔔 Alerts <span class="alert-badge" id="alertBadge" style="display:none">0</span>
         </button>